Log24

Tuesday, September 17, 2024

Brick Space Exercise

Filed under: General — Tags: — m759 @ 1:23 am

Thursday, August 15, 2024

Geometry Exercise

Filed under: General — m759 @ 11:00 pm

As G. M. Conwell pointed out in a 1910 paper, the group of all
40,320 permutations of an 8-element set is the same, in an
abstract sense, as the group of all collineations and dualities
of PG(3,2), the projective 3-space over the 2-element field.

This suggests we study the geometry related to the above group's
actions on the 105 partitions of an 8-set into four separate 2-sets.

Note that 105 equals 15×7 and also 35×3.

In such a study, the 15 points of PG(3,2) might correspond (somehow)
to 15 pairwise-disjoint seven-element subsets of the set of 105 partitions,
and the 35 lines of PG(3,2) might correspond (somehow) to 35 pairwise-
disjoint three-element subsets of the set of 105 partitions.

Exercise:  Is this a mere pipe dream?

A search for such a study yields some useful background . . .

.

Taylor's Index of Names  includes neither Conwell nor the
more recent, highly relevant, names Curtis  and Conway .

Monday, April 8, 2024

Variation on a Geometry Exercise

Filed under: General — Tags: — m759 @ 8:50 pm

Saturday, April 6, 2024

An Exercise in Figurate Geometry

Filed under: General — Tags: , — m759 @ 5:32 pm

Friday, May 26, 2023

Capilla Abierta : An Exercise in Bulk Apperception

Filed under: General — Tags: , — m759 @ 9:36 am

The previous post suggests a review . . .

'Saddle Chapel' at Cuernavaca

The above remarks on topology  are, of course, about as well-informed
as the remarks of Barry Mazur on locales .

Sunday, March 20, 2022

Mathieu Cube Exercise, Continued

Filed under: General — Tags: , , — m759 @ 3:39 pm

From February 26

Click to enlarge.

One approach to the above exercise —

Click to enlarge.

Saturday, October 30, 2021

Exercise

Filed under: General — m759 @ 11:47 am

"Show all your work."

"No problema."

Friday, August 14, 2020

Exercise

Filed under: General — Tags: , — m759 @ 11:00 pm

I prefer the boom box above to the one in Old Wives’ Tale (Aug. 10).

Tuesday, November 12, 2019

Exercise

Filed under: General — Tags: — m759 @ 2:26 am

Wednesday, August 28, 2019

Exercise

Filed under: General — Tags: , — m759 @ 4:44 pm

Friday, April 15, 2011

Exercise

Filed under: General — Tags: — m759 @ 2:00 am

The April Scientific American  on the partition function p (n )

"… in January, Ono and another collaborator [Bruinier] described the first formula that directly calculates p (n ) for any n, a feat that had eluded number theorists for centuries."

Exercise: Is this remarkable claim true or false?

For commentary here, see Jan. 27, "Indiana Jones and the Magical Oracle."

For further comments (the most recent from March 11), see mathoverflow.net, "Exact formulas for the partition function?"

Sunday, June 9, 2024

The Lo Shu Triangle  (洛書 三角形)

Filed under: General — Tags: , — m759 @ 10:11 am

Exercise Show that Dürer's 1514 "magic" square is an affine automorphism.

For a solution, see other posts now tagged Affine Squares.

Tuesday, January 30, 2024

Cullinane Diamond Theorem:
The Latest Google Bard Version

Filed under: General — Tags: , , , — m759 @ 7:00 am
 

Prompt:

What is the Cullinane diamond theorem?

Google Bard Response:

The Cullinane diamond theorem is a fascinating result in the realm of finite projective geometry and symmetry. It focuses on a specific pattern – the four-diamond figure – and reveals a surprising property about its transformations.

The Four-Diamond Figure:

Imagine a 4×4 grid filled with 16 small squares, half colored black and half white. Now, divide these squares diagonally into quarters, creating four diamonds with alternating black and white shades. This arrangement is the four-diamond figure.

_________________


[Clearly erroneous illustration with link to amazon.com
is omitted.]

_____________________

The Theorem:

The Cullinane diamond theorem states that no matter how you scramble this four-diamond figure by randomly shuffling rows, columns, and the four 2×2 quadrants, the resulting pattern will always exhibit some form of symmetry. This symmetry can come in two forms:

Ordinary symmetry: This is the familiar reflectional symmetry where a vertical or horizontal axis divides the pattern into mirrored halves.

Color-interchange symmetry: Here, the pattern has a diagonal axis where swapping the black and white colors results in the same image.

Intriguing Implications:

This statement might seem intuitive at first. After all, even with scrambling, some semblance of order should remain. However, the beauty of the Cullinane diamond theorem lies in its generality and the precise mathematical framework it provides for understanding these symmetries.

The theorem sheds light on the underlying structure of graphic patterns and connects them to concepts from finite projective geometry. This connection allows us to analyze and classify these patterns in a systematic way, revealing hidden connections and surprising symmetries.

Applications and Beyond:

The Cullinane diamond theorem has found applications in various areas, including:

Sporadic simple groups: The Miracle Octad Generator, used to study these rare and exceptional groups, relies on the symmetry properties outlined in the theorem.

Orthogonal Latin squares: The connection between orthogonal Latin squares and projective spreads can be understood through the lens of the Cullinane diamond theorem.

Walsh functions: The symmetry properties of Walsh functions, used in signal processing and coding theory, can be linked to the diamond patterns.

Understanding the Cullinane diamond theorem offers a deeper appreciation for the interplay between symmetry, geometry, and seemingly random patterns. It serves as a testament to the beauty and hidden order within the realm of mathematics.

Bard may display inaccurate info, including . . . .

[Exercise … Find any inaccurate information
in the Bard response above.]

Thursday, January 11, 2024

X-Post

Filed under: General — Tags: , , , — m759 @ 3:52 pm

See also "Opening the Local/Global Seal," Log24, March 8, 2023.

Sunday, December 3, 2023

The Star Brick

Filed under: General — Tags: , — m759 @ 8:06 pm

Saturday, November 18, 2023

“Don’t solicit for your sister,* it’s not nice.” — Tom Lehrer

Filed under: General — Tags: — m759 @ 11:36 am

André Weil to his sister:

From this journal at 1:51 AM  ET Thursday, September 8, 2022

"The pleasure comes from the illusion" . . .

Exercise:

Compare and contrast the following structure with the three
"bricks" of the R. T. Curtis Miracle Octad Generator (MOG).

http://www.log24.com/log/pix11B/110805-The24.jpg

Note that the 4-row-2-column "brick" at left is quite 
different from the other two bricks, which together
show chevron variations within a Galois tesseract —

.

Further Weil remarks . . .

A Slew of Prayers

"The pleasure comes from the illusion
and the far from clear meaning;
once the illusion is dissipated,
and knowledge obtained, one becomes
indifferent at the same time;
at least in the Gitâ there is a slew of prayers
(slokas) on the subject, each one more final
than the previous ones."

*

Saturday, August 19, 2023

Speak, Memory: The Jewel in Ray Houchins’s Lotus

Filed under: General — m759 @ 5:21 pm

"Does the name 'Coulter' mean anything to you?"

See as well this  journal on 07/19/2021, the Lotus-page date above. 

Wednesday, May 3, 2023

Art Lesson for Doktor Faustus

Filed under: General — Tags: , , — m759 @ 9:16 pm

Exercise Show that Dürer's 1514 "magic" square is an affine automorphism.

For a solution, see other posts now tagged Affine Squares.

Tuesday, April 11, 2023

AI Studies

Filed under: General — Tags: , — m759 @ 11:08 am

Google's new update page for its Bard AI experiment yesterday:

"We've updated Bard with better capabilities for math and logic."

Better, but still faulty.

Exercise: Correct the errors in the following —

(The worst errors are "1997" and "inspired by.")

Friday, February 10, 2023

Interstices and Symmetry

Filed under: General — Tags: , — m759 @ 10:02 am

Call a 4×4 array labeled with 4 copies each
of 4 different symbols a foursquare.

The symmetries of foursquares are governed
by the symmetries of their 24 interstices

The 24 interstices of a 4x4 array

(Cullinane, Diamond Theory, 1976.)

From Log24 posts tagged Mathieu Cube

A similar exercise might involve the above 24 interstices of a 4×4 array.

Saturday, January 21, 2023

Dead-Poet Witcraft

Filed under: General — Tags: , , — m759 @ 2:40 pm

"Death is the mother of beauty." — Wallace Stevens

From the 2020 Feast of St. Wallace Stevens,
who reportedly died in 1955 on August 2 —

Related material —

Durer magic square as an affine transformation

Exercise Can each  order-4 magic square be obtained by some
transformation like the one above (i.e., preserving affine hyperplanes)?
If not, why not?

Update of 31 Jan. 2023 — Spoiler Remarks by Tilman Piesk.

Tuesday, December 13, 2022

In Memory of a Mississippi Coach

Filed under: General — Tags: , — m759 @ 1:10 pm

Remarks in memory of football coach Mike Leach of Mississippi State University

The "Boolean exclusive or" is the same as addition 
in the two-element Galois field GF(2).

Saturday, November 12, 2022

Inside a White Cube

Filed under: General — Tags: — m759 @ 12:09 pm

For the late Brian O'Doherty, from posts now tagged "Pless Birthday 2022" —

A Mathieu Puzzle: 24 Diamond Facets of the Eightfold Cube

This post was suggested by an obituary of O'Doherty and by
"The Life and Work of Vera Stepen Pless" in
Notices of the American Mathematical Society , December 2022.

Tuesday, November 1, 2022

From “Goethe on All Souls’ Day”

Filed under: General — Tags: — m759 @ 3:04 am

The above title is that of a Log24 post on St. Cecilia's Day in 2017
that quoted some earlier All Souls' Day remarks from Berlin.

From that post —

Exercise:  Explain why the lead article in the November issue of
Notices of the American Mathematical Society  misquotes Weyl
and gives the misleading impression that the example above,
the eightfold cube ,  might be part of the mathematical pursuit
known as geometric group theory .

    Background:  Earlier instances here  of the phrase "geometric group theory." 

Thursday, September 29, 2022

The 4×6 Problem*

Filed under: General — Tags: , — m759 @ 4:03 pm

The exercise posted here on Sept. 11, 2022, suggests a 
more precisely stated problem . . .

The 24 coordinate-positions of the 4096 length-24 words of the 
extended binary Golay code G24 can be arranged in a 4×6 array
in, of course, 24! ways.

Some of these ways are more geometrically natural than others.
See, for instance, the Miracle Octad Generator of R. T. Curtis.
What is the size of the largest subcode C of G24 that can be 
arranged in a 4×6 array in such a way that the set  of words of C 
is invariant under the symmetry group of the rectangle itself, i.e. the
four-group of the identity along with horizontal and vertical reflections
and 180-degree rotation.

Recent Log24 posts tagged Bitspace describe the structure of
an 8-dimensional (256-word) code in a 4×6 array that has such
symmetry, but it is not yet clear whether that "cube-motif" code
is a Golay subcode. (Its octads are Golay, but possibly not all its
dodecads; the octads do not quite generate the entire code.) 
Magma may have an answer, but I have had little experience in
its use.

* Footnote of 30 September 2022.  The 4×6 problem is a
special case of a more general symmetric embedding problem.
Given a linear code C and a mapping of C to parts of a geometric
object A with symmetry group G, what is the largest subcode of C
invariant under G? What is the largest such subcode under all
such mappings from C to A?

Tuesday, September 20, 2022

Raiders of the Lost Space… Continues.

Filed under: General — Tags: — m759 @ 7:22 pm

From "Raiders of the Lost Space," Sept. 11, 2022 —

'Codes from Symmetry Groups,' Cheng and Sloane, 1989

A related technique appears in a 1989 paper by Cheng and Sloane
that I saw for the first time today:

'Codes from Symmetry Groups,' Cheng and Sloane, 1989

Wednesday, September 14, 2022

A Linear Code with 4×6 Symmetry

Filed under: General — Tags: — m759 @ 12:03 pm

The exercise of 9/11 continues . . .

From 'A Linear Code with 4x6 Symmetry,' a weblog post on 14 Sept. 2022.

As noted in an update at the end of the 9/11 post,
these 24 motifs, along with 3 bricks and 4 half-arrays,
generate a linear code of 12 dimensions. I have not
yet checked the code's minimum weight. 

Tuesday, September 13, 2022

A Helpful Survey of the Literature

Filed under: General — Tags: — m759 @ 9:39 pm

Some background for the exercise of 9/11

Vera Pless, "More on the uniqueness of the Golay codes,"
Discrete Mathematics 106/107 (1992) 391-398 —

"Several people [1-2,6] have shown that
any set of 212 binary vectors of length 24,
distance ≥ 8, containing 0, must be the
unique (up to equivalence) [24,12,8] Golay code." 

[1] P. Delsarte and J.M. Goethals, "Unrestricted codes
with the Golay parameters are unique
,"
Discrete Math. 12 (1975) 211-224.

[2] A. Neumeier, private communication, 1990.

[6] S.L. Snover, "The uniqueness of the
Nordstrom-Robinson and the Golay binary codes
,"
Ph.D. Thesis, Dept. of Mathematics, 
Michigan State Univ., 1973.

Related images —

"Before time began, there was the Cube."

              — Optimus Prime in 2007

      

"Remember, remember the fifth of November"

  — Hugo Weaving in 2005

Sunday, September 11, 2022

Raiders of the Lost Space

Filed under: General — Tags: , — m759 @ 2:29 pm

From 1981 —

From today —

Update —

A Magma check of the motif-generated space shows that
its dimension is only 8, not 12 as with the MOG space.
Four more basis vectors can be added to the 24 motifs to
bring the generated space up to 12 dimensions: the left
brick, the middle brick, the top half (2×6), the left half (4×3).
I have not yet checked the minimum weight in the resulting
12-dimensional 4×6 bit-space.

— SHC 4 PM ET, Sept. 12, 2022.

Thursday, September 8, 2022

Analogy in Mathematics: Chevron Variations

André Weil in 1940 on analogy in mathematics —

. "Once it is possible to translate any particular proof from one theory to another, then the analogy has ceased to be productive for this purpose; it would cease to be at all productive if at one point we had a meaningful and natural way of deriving both theories from a single one. In this sense, around 1820, mathematicians (Gauss, Abel, Galois, Jacobi) permitted themselves, with anguish and delight, to be guided by the analogy between the division of the circle (Gauss’s problem) and the division of elliptic functions. Today, we can easily show that both problems have a place in the theory of abelian equations; we have the theory (I am speaking of a purely algebraic theory, so it is not a matter of number theory in this case) of abelian extensions. Gone is the analogy: gone are the two theories, their conflicts and their delicious reciprocal reflections, their furtive caresses, their inexplicable quarrels; alas, all is just one theory, whose majestic beauty can no longer excite us. Nothing is more fecund than these slightly adulterous relationships; nothing gives greater pleasure to the connoisseur, whether he participates in it, or even if he is an historian contemplating it retrospectively, accompanied, nevertheless, by a touch of melancholy. The pleasure comes from the illusion and the far from clear meaning; once the illusion is dissipated, and knowledge obtained, one becomes indifferent at the same time; at least in the Gitâ there is a slew of prayers (slokas) on the subject, each one more final than the previous ones."

"The pleasure comes from the illusion" . . .

Exercise:

Compare and contrast the following structure with the three
"bricks" of the R. T. Curtis Miracle Octad Generator (MOG).

http://www.log24.com/log/pix11B/110805-The24.jpg

Note that the 4-row-2-column "brick" at left is quite 
different from the other two bricks, which together
show chevron variations within a Galois tesseract —

Saturday, September 3, 2022

1984 Revisited

Filed under: General — m759 @ 2:46 pm

Cube Bricks 1984 —

An Approach to Symmetric Generation of the Simple Group of Order 168

Related material

Note the three quadruplets of parallel edges  in the 1984 figure above.

Further Reading

The above Gates article appeared earlier, in the June 2010 issue of
Physics World , with bigger illustrations. For instance —

Exercise: Describe, without seeing the rest of the article,
the rule used for connecting the balls above.

Wikipedia offers a much clearer picture of a (non-adinkra) tesseract —

      And then, more simply, there is the Galois tesseract

For parts of my own  world in June 2010, see this journal for that month.

The above Galois tesseract appears there as follows:

Image-- The Dream of the Expanded Field

See also the Klein correspondence in a paper from 1968
in yesterday's 2:54 PM ET post

Wednesday, June 1, 2022

The Yearning

Filed under: General — Tags: — m759 @ 3:20 pm

" every sufficiently good analogy is yearning to become a functor."
— John Baez, 2004:  "Lessons from Topological Quantum Field Theory"

Related images — Quoting scripture at The Master's University
on Jan. 31, 2017 —

and some images (re)posted here on that same date — Jan. 31, 2017:

A related analogy — Between (1) and (2) below —

  1. A right triangle A as the sum of two smaller, 
    inner, right triangles B and C, each similar to A .
  2. The square on the longest side of A as the sum
    of the squares on the longest sides of B and C.

Exercise for Baez fans Express the above analogy as a functor.

Saturday, March 5, 2022

Word and World*

Filed under: General — Tags: — m759 @ 11:28 pm

This afternoon's post with the phrase
"Eternal Word Meets Eternal World" 
suggests a book

A search in this journal for "world within" yields . . .

"Instead of the 'static spacetime jewel' of blockworld that is often invoked by eternalists to help their readers conceptualize of what a blockworld would 'look like' from the outside, now imagine that a picture on a slide is being projected onto the surface of this space-time jewel.

From the perspective of one inside the jewel, one might ask 'Why is this section blue while this section is black?,' and from within the jewel, one could not formulate an answer since one could not see the entire picture projected on the jewel; however, from outside the jewel, an observer (some analogue of Newton's God, perhaps, looking down on his 'sensorium' from the 5th dimension) could easily see the pattern and understand that all of the 'genuinely fortuitous' events inside the space-time jewel are, in fact, completely determined by the pattern in the projector."

— "Genuine Fortuitousness, Relational Blockworld, Realism, and Time" (pdf), by Daniel J. Peterson, Honors Thesis, Swarthmore College, December 13, 2007, footnote 55, page 114

A related image from pure  mathematics —

The Mathieu Cube Puzzle

* The title is thanks to William Gass.

Saturday, February 26, 2022

Beyond Rubik: The Mathieu Cube

Filed under: General — Tags: , — m759 @ 1:18 pm

Click to enlarge.

Saturday, February 5, 2022

Mathieu Cube Labeling

Filed under: General — Tags: , , , , — m759 @ 2:08 pm

Shown below is an illustration from "The Puzzle Layout Problem" —

Exercise:  Using the above numerals 1 through 24
(with 23 as 0 and 24 as ∞) to represent the points 
, 0, 1, 2, 3 … 22  of the projective line over GF(23),
reposition the labels 1 through 24 in the above illustration
so that they appropriately* illustrate the cube-parts discussed
by Iain Aitchison in his March 2018 Hiroshima slides on 
cube-part permutations by the Mathieu group M24

A note for Northrop Frye —

Interpenetration in the eightfold cube — the three midplanes —

IMAGE- The Trinity Cube (three interpenetrating planes that split the eightfold cube into its eight subcubes)

A deeper example of interpenetration:

Aitchison has shown that the Mathieu group M24 has a natural
action on the 24 center points of the subsquares on the eightfold
cube's six faces (four such points on each of the six faces). Thus
the 759 octads of the Steiner system S(5, 8, 24) interpenetrate
on the surface of the cube.

* "Appropriately" — I.e. , so that the Aitchison cube octads correspond
exactly, via the projective-point labels, to the Curtis MOG octads.

Friday, September 17, 2021

Adventures in Mix-and-Match Reality . . .

Filed under: General — Tags: , , — m759 @ 10:36 am

Continued from September 8 .

The New York Times  yesterday

“Art is another way to try to exercise your imagination
at connecting incongruous things,” Anthony Doerr said.
“It’s a way to say, hey, reader, let’s work together and
practice and train our imagination to connect things
that you don’t readily think of as connected.”

Sunday, August 15, 2021

Simple Similarity

Filed under: General — Tags: , , , — m759 @ 1:05 pm

The following image (click to enlarge) is now the target of
a link on the phrase "similarly divided" in Friday's post
"The Divided Square."

Related material —

A version of the above Schroeder pages, dumbed down for
readers of The New Yorker

Note  that the proof under discussion has nothing to do with 
the New Yorker 's rubric "Annals of Technology."

Note also the statement by Strogatz that 

"Einstein’s proof reveals why the Pythagorean theorem
applies only to right triangles: they’re the only kind
made up of smaller copies of themselves." 

Exercise:  Discuss the truth or falsity of the Strogatz statement
after reviewing the webpage Triangles Are Square.

For approaches to geometry that are more advanced, see
this  journal on the above New Yorker  date — Nov. 19, 2015 —

Highlights of the Dirac-Mathieu Connection.

 
 

Saturday, January 23, 2021

Tiny Dancer

Filed under: General — Tags: — m759 @ 12:45 am

The above image was suggested by a link in a
Philadelphia Inquirer  obituary from yesterday evening.

Exercise: What is controlled by the middle-finger string?

Thursday, February 20, 2020

In Memory of Hunter S. Thompson

Filed under: General — Tags: — m759 @ 2:45 pm

“Continue to exercise caution with stories that can only be
corroborated by dead guys."

— Intelligence officer Frank Anderson in the previous post.

Tale

Filed under: General — Tags: , — m759 @ 12:45 am

“Continue to exercise caution with stories that can only be
corroborated by dead guys. Fabricated stories are almost
never made up out of whole cloth, but are made by stitching
together generally known facts with bits of uncheckable fantasy.”

— Intelligence officer Frank Anderson, who reportedly
died on January 27, 2020.

This journal on that date

Sunday, December 22, 2019

M24 from the Eightfold Cube

Exercise:  Use the Guitart 7-cycles below to relate the 56 triples
in an 8-set (such as the eightfold cube) to the 56 triangles in
a well-known Klein-quartic hyperbolic-plane tiling. Then use
the correspondence of the triples with the 56 spreads of PG(3,2)
to construct M24.

Click image below to download a Guitart PowerPoint presentation.

See as well earlier posts also tagged Triangles, Spreads, Mathieu.

Friday, December 6, 2019

Cezanne’s Greetings

Filed under: General — Tags: — m759 @ 12:18 pm

David Corfield on "Aesthetic Theory and Artistic Practice" —

" British naturalism of the nineteenth century is seen to be
based on a theory of art whose origin lies in eighteenth century
philosophy. Collingwood believes this to be a false theory,
as first made clear artistically by Cezanne. Note also that
Collingwood should feel the need to depart from abstract
argument to include the case study.

Exercise: with minimal changes make the above true for
the philosophy of mathematics. Once done, we see how
we should expect to find a philosophy of mathematics
in each mathematician, even if it only functions implicitly.
See Philosophy as Normative or Descriptive.

Last revised on July 12, 2010 at 11:02:44."

See as well some philosophical remarks by the late
William J. Richardson, S.J., quoted here  on July 12, 2010.

Tuesday, October 29, 2019

Triangles, Spreads, Mathieu

Filed under: General — Tags: , , — m759 @ 8:04 pm

There are many approaches to constructing the Mathieu
group M24. The exercise below sketches an approach that
may or may not be new.

Exercise:

It is well-known that

 There are 56 triangles in an 8-set.
There are 56 spreads in PG(3,2).
The alternating group An is generated by 3-cycles.
The alternating group Ais isomorphic to GL(4,2).

Use the above facts, along with the correspondence
described below, to construct M24.

Some background —

A Log24 post of May 19, 2013, cites

Peter J. Cameron in a 1976 Cambridge U. Press
book — Parallelisms of Complete Designs .
See the proof of Theorem 3A.13 on pp. 59 and 60.

See also a Google search for "56 triangles" "56 spreads" Mathieu.

Update of October 31, 2019 — A related illustration —

Update of November 2, 2019 —

See also p. 284 of Geometry and Combinatorics:
Selected Works of J. J. Seidel
  (Academic Press, 1991).
That page is from a paper published in 1970.

Update of December 20, 2019 —

Thursday, August 15, 2019

Schoolgirl Space — Tetrahedron or Square?

Filed under: General — Tags: , , — m759 @ 9:03 pm

The exercise in the previous post  was suggested by a passage
purporting to "use standard block design theory" that was written
by some anonymous author at Wikipedia on March 1, 2019:

Here "rm OR" apparently means "remove original research."

Before the March 1 revision . . .

The "original research" objected to and removed was the paragraph
beginning "To explain this further."  That paragraph was put into the
article earlier on Feb. 28 by yet another anonymous author (not  by me).

An account of my own (1976 and later) original research on this subject 
is pictured below, in a note from Feb. 20, 1986 —

'The relativity problem in finite geometry,' 1986

On Steiner Quadruple Systems of Order 16

Filed under: General — Tags: , — m759 @ 4:11 am

An image from a Log24 post of March 5, 2019

Cullinane's 1978  square model of PG(3,2)

The following paragraph from the above image remains unchanged
as of this morning at Wikipedia:

"A 3-(16,4,1) block design has 140 blocks of size 4 on 16 points,
such that each triplet of points is covered exactly once. Pick any
single point, take only the 35 blocks containing that point, and
delete that point. The 35 blocks of size 3 that remain comprise
a PG(3,2) on the 15 remaining points."

Exercise —

Prove or disprove the above assertion about a general "3-(16,4,1) 
block design," a structure also known as a Steiner quadruple system
(as I pointed out in the March 5 post).

Relevant literature —

A paper from Helsinki in 2005* says there are more than a million
3-(16,4,1) block designs, of which only one has an automorphism
group of order 322,560. This is the affine 4-space over GF(2),
from which PG(3,2) can be derived using the well-known process
from finite geometry described in the above Wikipedia paragraph.

* "The Steiner quadruple systems of order 16," by Kaski et al.,
   Journal of Combinatorial Theory Series A  
Volume 113, Issue 8, 
   November 2006, pages 1764-1770.

Monday, February 25, 2019

The Sartwell Illusion

Filed under: General — Tags: — m759 @ 2:56 pm

See Sartwell in this journal and . . .

"Read something that means something." — New Yorker  motto.

From a search for Alperin in this  journal —

http://www.log24.com/log/pix18/180824-Alperin-Groups_and_Representations-1995-p61-Further_Exercises.jpg

Why PSL(2,7) is isomorphic to GL(3.2)

Sunday, December 23, 2018

See!

Filed under: General — Tags: , — m759 @ 8:40 pm

An exercise in bulk apperception.

IMAGE- Herbert John Ryser, 'Combinatorial Mathematics' (1963), page 1

Saturday, August 25, 2018

Point at Infinity

Filed under: General,Geometry — Tags: , — m759 @ 5:20 am

In literature —

http://www.log24.com/log/pix18/180825-Point_Omega-cover.jpg

In film —

http://www.log24.com/log/pix18/180825-Borrego-script-Instagram-foto-only-500w.jpg

In mathematics —

http://www.log24.com/log/pix18/180824-Alperin-Groups_and_Representations-1995-p61-Further_Exercises.jpg

Wednesday, July 18, 2018

Mira and the Intruders* Present …

Filed under: General — Tags: , , — m759 @ 9:11 pm

Epiphany 2012: An Exercise
in Bulk Apperception

This post was suggested by . . .
a New Orleans song as played by Bix Beiderbecke,
by a trailer for a new Zemeckis film that appeared at YouTube
on the way to the New Orleans song, and by
the longing for Bix by Mira Sorvino in "Intruders."

The YouTube Bix date, Jan. 6, 2012, suggested a trip back
to that date via a Zemeckis Cube (see "Ready Player One.")

From Log24 on Epiphany 2012

IMAGE- Cathy Hull, detail from cover of Hillman's 'The Dream and the Underworld'

A version of the Zemeckis Cube

From the Zemeckis trailer —

* See a Log24 search for Mira + Intruders.

Wednesday, March 21, 2018

WISC RISC

Filed under: General,Geometry — Tags: — m759 @ 2:15 pm

WISC = Wechsler Intelligence Scale for Children

RISCReduced Instruction Set Computer   or
             Rust Inventory of Schizotypal Cognitions

See related material in earlier WISC RISC posts.

See also . . .

"Many parents ask us about the Block Design section
on the WISC and hope to purchase blocks and exercises
like those used on the WISC test. We explain that doing that
has the potential to invalidate their child's test results.
These Froebel Color Cubes will give you a tool to work with
your child on the skills tested for in the Block Design section
of the WISC in an ethical and appropriate way. These same
skills are applicable to any test of non-verbal reasoning like  
the NNAT, Raven's or non-verbal sections of the CogAT or OLSAT. "

An online marketing webpage

For a webpage that is perhaps un ethical and in appropriate,
see Block Designs in Art and Mathematics.

Tuesday, August 8, 2017

July 29 Podcast

Filed under: General — Tags: — m759 @ 6:26 pm

Exercise:

Discuss whether Knudson's phrase "essentially says" is correct.

For the Church of Synchronology

The above Forbes article is dated July 29, the date of death for 
Landon T. Clay, founder of Clay Mathematics Institute.

For remarks related to that date, see posts tagged Prize Problem
in this  journal.

Tuesday, July 11, 2017

A Date at the Death Cafe

Filed under: General,Geometry — Tags: , — m759 @ 8:48 pm

The New York TImes  reports this evening that
"Jon Underwood, Founder of Death Cafe Movement,"
died suddenly at 44 on June 27. 

This  journal on that date linked to a post titled "The Mystic Hexastigm."

A related remark on the complete 6-point   from Sunday, April 28, 2013

(See, in Veblen and Young's 1910 Vol. I, exercise 11,
page 53: "A plane section of a 6-point in space can  
be considered as 3 triangles perspective in pairs
from 3 collinear points with corresponding sides
meeting in 3 collinear points." This is the large  
Desargues configuration. See Classical Geometry
in Light of Galois Geometry
.)

This  post was suggested, in part, by the philosophical ruminations
of Rosalind Krauss in her 2011 book Under Blue Cup . See 
Sunday's post  Perspective and Its Transections . (Any resemblance
to Freud's title Civilization and Its Discontents  is purely coincidental.)

Saturday, June 10, 2017

Cardinal Interplay

Filed under: General — m759 @ 12:28 pm

Exercise — Translate "cardinal interplay."

Related material — Language animal in this journal.

Monday, May 15, 2017

Appropriation at MoMA

Filed under: General,Geometry — m759 @ 1:14 pm

For example, Plato's diamond as an object to be transformed —

Plato's diamond in Jowett's version of the Meno dialogue

Versions of the transformed object —

See also The 4×4 Relativity Problem in this journal.

Monday, February 20, 2017

Tetrad

Filed under: General — Tags: , — m759 @ 10:31 pm

Wiktionary —

Russian noun . . .

тетра́дь   (tetrádʹ)  f  inan 
(genitive  тетра́ди
nominative plural  тетра́ди
genitive plural  тетра́дей)

Etymology

Borrowing from Ancient Greek τετράδιον  ‎(tetrádion, 
“quaternion of parchment”), from τετράς  ‎(tetrás),

Noun

  1.  exercise book, notebook


See also Tetrad in this journal.

Thursday, February 16, 2017

Nested Projective Structures

Filed under: General,Geometry — m759 @ 11:00 pm

Two views of nested sequences of projective structures —

From this journal in April 2013:

From the arXiv in September 2014

Saniga's reference [6] is to a paper submitted to the arXiv in May 2014. 

My own note of April 30, 2013, concludes with an historical reference
that indicates the mathematics underlying both my own and Saniga's
remarks —

The exercises at the end of Ch. II in Veblen and Young's 
Projective Geometry, Vol. I  (Ginn, 1910). For instance:

Sunday, February 12, 2017

Religious Art for Sunday

Filed under: General,Geometry — Tags: — m759 @ 11:02 am

Euclidean  square and triangle

Galois  square and triangle

For some backstory, see the "preface" of the 
previous post and Soifer in this journal.

Wednesday, December 28, 2016

Rosetta Tesseracts

Filed under: General — m759 @ 9:00 am

Click to enlarge.

Related material Folk Etymology  (Dec. 10, 2016).

Monday, December 19, 2016

Tetrahedral Cayley-Salmon Model

Filed under: General,Geometry — Tags: , — m759 @ 9:38 am

The figure below is one approach to the exercise
posted here on December 10, 2016.

Tetrahedral model (minus six lines) of the large Desargues configuration

Some background from earlier posts —


IMAGE- Geometry of the Six-Set, Steven H. Cullinane, April 23, 2013

Click the image below to enlarge it.

Polster's tetrahedral model of the small Desargues configuration

Saturday, December 17, 2016

The Exercist

Filed under: General — m759 @ 9:26 am

See Exercise in this journal.
Happy birthday to Pope Francis.

Friday, December 16, 2016

Read Something That Means Something

Filed under: General,Geometry — Tags: , — m759 @ 5:29 pm

Saturday, December 10, 2016

Folk Etymology

Images from Burkard Polster's Geometrical Picture Book

See as well in this journal the large  Desargues configuration, with
15 points and 20 lines instead of 10 points and 10 lines as above.

Exercise:  Can the large Desargues configuration be formed
by adding 5 points and 10 lines to the above Polster model
of the small configuration in such a way as to preserve
the small-configuration model's striking symmetry?  
(Note: The related figure below from May 21, 2014, is not
necessarily very helpful. Try the Wolfram Demonstrations
model
, which requires a free player download.)

Labeling the Tetrahedral Model (Click to enlarge) —

Related folk etymology (see point a  above) —

Related literature —

The concept  of "fire in the center" at The New Yorker , 
issue dated December 12, 2016, on pages 38-39 in the
poem by Marsha de la O titled "A Natural History of Light."

Cézanne's Greetings.

Saturday, August 6, 2016

Mystic Correspondence:

Filed under: General,Geometry — Tags: — m759 @ 12:00 pm

The Cube and the Hexagram

The above illustration, by the late Harvey D. Heinz,
shows a magic cube* and a corresponding magic 
hexagram, or Star of David, with the six cube faces 
mapped to the six hexagram lines and the twelve  
cube edges mapped to the twelve hexagram points.
The eight cube vertices correspond to eight triangles
in the hexagram (six small and two large). 

Exercise:  Is this noteworthy mapping** of faces to lines, 
edges to points, and vertices to triangles an isolated 
phenomenon, or can it be viewed in a larger context?

* See the discussion at magic-squares.net of
   "perimeter-magic cubes"

** Apparently derived from the Cube + Hexagon figure
    discussed here in various earlier posts. See also
    "Diamonds and Whirls," a note from 1984.

Monday, April 11, 2016

Gospel of the Nobodies

Filed under: General — Tags: , — m759 @ 2:56 pm

"Principles before personalities" — AA saying

Principles

From an April 8 Princeton obituary of a mathematician —

" Moore embodied a 'Princeton style' that made him
a challenging and influential presence in the careers
of his students, said Joseph Neisendorfer, a professor
of mathematics at the University of Rochester who
received his Ph.D. in mathematics from Princeton in
1972. Because of Moore's style, his students would
write theses that 'almost without exception' were
significant advances in mathematics, Neisendorfer said.

'There's a certain Princeton style that focuses on
precision, centrality and simplicity. He was a superb
mathematician and he exercised a lot of influence
by imparting his style to his students,' Neisendorfer said.
'He epitomized the Princeton style.' "

Personalities 

Gospel of the Nobodies 

Friday, March 4, 2016

Chess by Other Means

Filed under: General — m759 @ 7:22 pm

On film director Stanley Kubrick:

From "Kubrick," by Michael Herr, Vanity Fair , August 1999—

"He disliked the usual references to his having been a 'chess hustler' in his Greenwich Village days, as though this impugned the gravity and beauty of the exercise, the suggestion that his game wasn’t pour le sport  or, more correctly, pour l’art . To win the game was important, to win the money was irresistible, but it was nothing compared with his game, with the searching, endless action of working on his game. But of course he was hustling, he was always hustling; as he grew older and moved beyond still photography, chess became movies, and movies became chess by other means. I doubt that he ever thought of chess as just a game, or even as a game at all. I do imagine that a lot of people sitting across the board from him got melted, fried, and fragmented when Stanley let that cool ray come streaming down out of his eyes— talk about penetrating looks and piercing intelligence; here they’d sat down to a nice game of chess, and all of a sudden he was doing the thinking for both of them."

On physics writer Peter Woit:

From Part II of an interview with Peter Woit by Gerald Alper
in Smashpipe  published March 1, 2016:

"For just a moment, he allows himself to become self reflective: 'I was always a smart kid. A very smart kid. I suppose if I ever took a standardized test I would do very well, especially, in the area of abstract reasoning.'

Peter Woit says this as matter-of-factly as if he said, 'When I was a kid my father drove a Chevrolet.' He says it as Kareem Abdul-Jabbar, if asked to describe how he became the person he is, might have said 'I was always a tall kid. A very tall kid. In school, short kids bored me.'

I felt I had to say, 'but there must be a few million people in the United States who would also score very high in abstract thinking in the standardized tests and none of them have your interests.'

'The people around here all do. And there are thousands of us all around the world.'

'But there are 7 billion people in the world.'

Peter Woit had to concede the mathematical point, but I don't think he appreciated the psychological distinction I was alluding to. There is an astonishing divide between the culture of science and the culture of humanities that C.P. Snow famously alluded to. There is even a greater divide between the culture of pure mathematics and the culture of the earthbound evolutionarily programmed biological world into which we are born.

There is a celebrated quip by Dick Cavett that encapsulates this. Reflecting on his famous interview of the then reigning world chess champion, Bobby Fischer, he observed:

'Throughout the interview I could feel the force of his IQ.'

Paraphrasing this I could say that throughout the interview, which was at times exhilarating, at times daunting, I could feel the force of his two hundred QMIQ (quantum mechanics IQ). Norman Mailer once commented that the immediacy of television— the fact that most influential people in the world can be brought into your living room— creates the illusion that you have thereby been included in their inner power circle, and to that extent vicariously empowered. But you are no closer to the corridors of power then you were before. Analogously, you can sit just a few feet away from a world-class expert, close enough to reach out and touch them, but you are no closer to their accumulated wisdom— unless you are willing to go home and put in ten thousand hours of hard work trying to raise the level of your understanding."

http://www.log24.com/log/pix09A/091109-Nicole.jpg

Illustration from a post of
Schicksalstag  2009

Tuesday, December 15, 2015

Square Triangles

Filed under: General,Geometry — Tags: , — m759 @ 3:57 pm

Click image for some background.

Exercise:  Note that, modulo color-interchange, the set of 15 two-color
patterns above is invariant under the group of six symmetries of the
equilateral triangle. Are there any other such sets of 15 two-color triangular
patterns that are closed as sets , modulo color-interchange, under the six
triangle symmetries and  under the 322,560 permutations of the 16
subtriangles induced by actions of the affine group AGL(4,2)
on the 16 subtriangles' centers , given a suitable coordinatization?

Saturday, September 19, 2015

Geometry of the 24-Point Circle

Filed under: General,Geometry — Tags: , , — m759 @ 1:13 am

The latest Visual Insight  post at the American Mathematical
Society website discusses group actions on the McGee graph,
pictured as 24 points arranged in a circle that are connected
by 36 symmetrically arranged edges.

Wikipedia remarks that

"The automorphism group of the McGee graph
is of order 32 and doesn't act transitively upon
its vertices: there are two vertex orbits of lengths
8 and 16."

The partition into 8 and 16 points suggests, for those familiar
with the Miracle Octad Generator and the Mathieu group M24,
the following exercise:

Arrange the 24 points of the projective line
over GF(23) in a circle in the natural cyclic order
, 1, 2, 3,  , 22, 0 ).  Can the McGee graph be
modeled by constructing edges in any natural way?

Image that may or may not be related to the extended binary Golay code and the large Witt design

In other words, if the above set of edges has no
"natural" connection with the 24 points of the
projective line over GF(23), does some other 
set of edges in an isomorphic McGee graph
have such a connection?

Update of 9:20 PM ET Sept. 20, 2015:

Backstory: A related question by John Baez
at Math Overflow on August 20.

Monday, August 17, 2015

Modern Algebra Illustrated

Filed under: General — m759 @ 10:06 am

For illustrations based on the above equations, see
Coxeter and the Relativity Problem  and Singer 7-Cycles .

Saturday, December 27, 2014

More To Be Done

Filed under: General,Geometry — m759 @ 1:44 am

  Ball and Weiner, 'An Introduction to Finite Geometry,' version of Sept. 5, 2011

The Ball-Weiner date above, 5 September 2011,
suggests a review of this journal on that date —

"Think of a DO NOT ENTER pictogram,
a circle with a diagonal slash, a type of ideogram.
It tells you what to do or not do, but not why.
The why is part of a larger context, a bigger picture."

— Customer review at Amazon.com

This passage was quoted here on August 10, 2009.

Also from that date:

The Sept. 5, 2011, Ball-Weiner paper illustrates the
"doily" view of the mathematical structure W(3,2), also
known as GQ(2,2), the Sp(4,2) generalized quadrangle.
(See Fig. 3.1 on page 33, exercise 13 on page 38, and
the answer to that exercise on page 55, illustrated by 
Fig. 5.1 on page 56.)

For "another view, hidden yet true," of GQ(2,2),
see Inscape and Symplectic Polarity in this journal.

Wednesday, November 26, 2014

Class Act

Filed under: General,Geometry — Tags: , — m759 @ 7:18 am

Update of Nov. 30, 2014 —

For further information on the geometry in
the remarks by Eberhart below, see
pp. 16-17 of A Geometrical Picture Book ,
by Burkard Polster (Springer, 1998). Polster
cites a different article by Lemay.

A search for background to the exercise in the previous post
yields a passage from the late Stephen Eberhart:

The first three primes p = 2, 3, and 5 therefore yield finite projective planes with 7, 13, and 31 points and lines, respectively. But these are just the numbers of symmetry axes of the five regular solids, as described in Plato's Timaeus : The tetrahedron has 4 pairs of face planes and corner points + 3 pairs of opposite edges, totalling 7 axes; the cube has 3 pairs of faces + 6 pairs of edges + 4 pairs of corners, totalling 13 axes (the octahedron simply interchanges the roles of faces and corners); and the pentagon dodecahedron has 6 pairs of faces + 15 pairs of edges + 10 pairs of corners, totalling 31 axes (the icosahedron again interchanging roles of faces and corners). This is such a suggestive result, one would expect to find it dealt with in most texts on related subjects; instead, while "well known to those who well know such things" (as Richard Guy likes to quip), it is scarcely to be found in the formal literature [9]. The reason for the common numbers, it turns out, is that the groups of symmetry motions of the regular solids are subgroups of the groups of collineations of the respective finite planes, a face axis being different from an edge axis of a regular solid but all points of a projective plane being alike, so the latter has more symmetries than the former.

[9] I am aware only of a series of in-house publications by Fernand Lemay of the Laboratoire de Didactique, Faculté des Sciences de I 'Éducation, Univ. Laval, Québec, in particular those collectively titled Genèse de la géométrie  I-X.

— Stephen Eberhart, Dept. of Mathematics,
California State University, Northridge, 
"Pythagorean and Platonic Bridges between
Geometry and Algebra," in BRIDGES: Mathematical
Connections in Art, Music, and Science 
, 1998,
archive.bridgesmathart.org/1998/bridges1998-121.pdf

Eberhart died of bone cancer in 2003. A memorial by his
high school class includes an Aug. 7, 2003, transcribed
letter from Eberhart to a classmate that ends…


… I earned MA’s in math (UW, Seattle) and history (UM, Missoula) where a math/history PhD program had been announced but canceled.  So 1984 to 2002 I taught math (esp. non-Euclidean geometry) at C.S.U. Northridge.  It’s been a rich life.  I’m grateful. 
 
Steve
 

See also another informative BRIDGES paper by Eberhart
on mathematics and the seven traditional liberal arts.

Tuesday, November 25, 2014

Euclidean-Galois Interplay

Filed under: General,Geometry — Tags: , , — m759 @ 11:00 am

For previous remarks on this topic, as it relates to
symmetry axes of the cube, see previous posts tagged Interplay.

The above posts discuss, among other things, the Galois
projective plane of order 3, with 13 points and 13 lines.

Oxley's 2004 drawing of the 13-point projective plane

These Galois points and lines may be modeled in Euclidean geometry
by the 13 symmetry axes and the 13 rotation planes
of the Euclidean cube. They may also be modeled in Galois geometry
by subsets of the 3x3x3 Galois cube (vector 3-space over GF(3)).

http://www.log24.com/log/pix11A/110427-Cube27.jpg

   The 3×3×3 Galois Cube 

Exercise: Is there any such analogy between the 31 points of the
order-5 Galois projective plane and the 31 symmetry axes of the
Euclidean dodecahedron and icosahedron? Also, how may the
31 projective points  be naturally pictured as lines  within the 
5x5x5 Galois cube (vector 3-space over GF(5))?

Update of Nov. 30, 2014 —

For background to the above exercise, see
pp. 16-17 of A Geometrical Picture Book ,
by Burkard Polster (Springer, 1998), esp.
the citation to a 1983 article by Lemay.

Monday, November 10, 2014

Narrative Line

Filed under: General,Geometry — Tags: , , — m759 @ 11:02 pm

"We live entirely, especially if we are writers, by the imposition
of a narrative line upon 
disparate images…." — Joan Didion

Narrative Line:

IMAGE- R. D. Carmichael's 1931 construction of the Steiner system S(5, 8, 24)

IMAGE- Harvard senior Jeremy Booher in 2010 discusses Carmichael's 1931 construction of S(5, 8, 24) without mentioning Carmichael.

Disparate images:

Exercise:

Can the above narrative line be imposed in any sensible way
upon the above disparate images?

Thursday, October 2, 2014

The Christmas Theorem

Filed under: General — Tags: — m759 @ 7:29 pm

From the preface to Introduction to the Construction of Class Fields ,
by Harvey Cohn (Cambridge University Press, 1985):

“It is an elementary observation that an integral right triangle
has an even area. Suppose the hypotenuse is prime.

Q.  How do we determine from the prime value of the hypotenuse
when the area is divisible by 4, 8, 16, or any higher power of 2?

A.  We use class fields constructed by means of transcendental
functions, of course!

The question might have been asked by Pythagoras in about
500 BC….”

The question seems to assume something apparently not known to Pythagoras:

The area is determined uniquely by the prime hypotenuse.

Nontrivial exercise: Prove or disprove this assertion.

Background to the exercise: See Fermat’s Christmas Theorem  on the Web,
and a specific remark about prime hypotenuses in a letter from Fermat to
Mersenne on Christmas Day, 1640, quoted in The Mathematical Career
of Pierre de Fermat, 1601-1665
 
, by Michael Sean Mahoney (Princeton
University Press, 2nd ed,, 1994), pp. 316-317.

Thursday, September 11, 2014

A Class by Itself

Filed under: General — Tags: , — m759 @ 9:48 am

The American Mathematical Society yesterday:

Harvey Cohn (1923-2014)
Wednesday September 10th 2014

Cohn, an AMS Fellow and a Putnam Fellow (1942), died May 16 at the age of 90. He served in the Navy in World War II and following the war received his PhD from Harvard University in 1948 under the direction of Lars Ahlfors. He was a member of the faculty at Wayne State University, Stanford University, Washington University in St. Louis, the University of Arizona, and at City College of New York, where he was a distinguished professor. After retiring from teaching, he also worked for the NSA. Cohn was an AMS member since 1942.

Paid death notice from The New York Times , July 27, 2014:

COHN–Harvey. Fellow of the American Mathematical Society and member of the Society since 1942, died on May 16 at the age of 90. He was a brilliant Mathematician, an adoring husband, father and grandfather, and faithful friend and mentor to his colleagues and students. Born in New York City in 1923, Cohn received his B.S. degree (Mathematics and Physics) from CCNY in 1942. He received his M.S. degree from NYU (1943), and his Ph.D. from Harvard (1948) after service in the Navy (Electronic Technicians Mate, 1944-46). He was a member of Phi Beta Kappa (Sigma Chi), won the William Lowell Putnam Prize in 1942, and was awarded the Townsend Harris Medal in 1972. A pioneer in the intensive use of computers in an innovative way in a large number of classical mathematical problems, Harvey Cohn held faculty positions at Wayne State University, Stanford, Washington University Saint Louis (first Director of the Computing Center 1956-58), University of Arizona (Chairman 1958-1967), University of Copenhagen, and CCNY (Distinguished Professor of Mathematics). After his retirement from teaching, he worked in a variety of capacities for the National Security Agency and its research arm, IDA Center for Computing Sciences. He is survived by his wife of 63 years, Bernice, of Laguna Woods, California and Ft. Lauderdale, FL, his son Anthony, daughter Susan Cohn Boros, three grandchildren and one great-granddaughter.

— Published in The New York Times  on July 27, 2014

See also an autobiographical essay found on the web.

None of the above sources mention the following book, which is apparently by this same Harvey Cohn. (It is dedicated to "Tony and Susan.")

From Google Books:

Advanced Number Theory, by Harvey Cohn
Courier Dover Publications, 1980 – 276 pages
(First published by Wiley in 1962 as A Second Course in Number Theory )

Publisher's description:

" 'A very stimulating book … in a class by itself.'— American Mathematical Monthly

Advanced students, mathematicians and number theorists will welcome this stimulating treatment of advanced number theory, which approaches the complex topic of algebraic number theory from a historical standpoint, taking pains to show the reader how concepts, definitions and theories have evolved during the last two centuries. Moreover, the book abounds with numerical examples and more concrete, specific theorems than are found in most contemporary treatments of the subject.

The book is divided into three parts. Part I is concerned with background material — a synopsis of elementary number theory (including quadratic congruences and the Jacobi symbol), characters of residue class groups via the structure theorem for finite abelian groups, first notions of integral domains, modules and lattices, and such basis theorems as Kronecker's Basis Theorem for Abelian Groups.

Part II discusses ideal theory in quadratic fields, with chapters on unique factorization and units, unique factorization into ideals, norms and ideal classes (in particular, Minkowski's theorem), and class structure in quadratic fields. Applications of this material are made in Part III to class number formulas and primes in arithmetic progression, quadratic reciprocity in the rational domain and the relationship between quadratic forms and ideals, including the theory of composition, orders and genera. In a final concluding survey of more recent developments, Dr. Cohn takes up Cyclotomic Fields and Gaussian Sums, Class Fields and Global and Local Viewpoints.

In addition to numerous helpful diagrams and tables throughout the text, appendices, and an annotated bibliography, Advanced Number Theory  also includes over 200 problems specially designed to stimulate the spirit of experimentation which has traditionally ruled number theory."

User Review –

"In a nutshell, the book serves as an introduction to Gauss' theory of quadratic forms and their composition laws (the cornerstone of his Disquisitiones Arithmeticae) from the modern point of view (ideals in quadratic number fields). I strongly recommend it as a gentle introduction to algebraic number theory (with exclusive emphasis on quadratic number fields and binary quadratic forms). As a bonus, the book includes material on Dirichlet L-functions as well as proofs of Dirichlet's class number formula and Dirichlet's theorem in primes in arithmetic progressions (of course this material requires the reader to have the background of a one-semester course in real analysis; on the other hand, this material is largely independent of the subsequent algebraic developments).

Better titles for this book would be 'A Second Course in Number Theory' or 'Introduction to quadratic forms and quadratic fields'. It is not a very advanced book in the sense that required background is only a one-semester course in number theory. It does not assume prior familiarity with abstract algebra. While exercises are included, they are not particularly interesting or challenging (if probably adequate to keep the reader engaged).

While the exposition is *slightly* dated, it feels fresh enough and is particularly suitable for self-study (I'd be less likely to recommend the book as a formal textbook). Students with a background in abstract algebra might find the pace a bit slow, with a bit too much time spent on algebraic preliminaries (the entire Part I—about 90 pages); however, these preliminaries are essential to paving the road towards Parts II (ideal theory in quadratic fields) and III (applications of ideal theory).

It is almost inevitable to compare this book to Borevich-Shafarevich 'Number Theory'. The latter is a fantastic book which covers a large superset of the material in Cohn's book. Borevich-Shafarevich is, however, a much more demanding read and it is out of print. For gentle self-study (and perhaps as a preparation to later read Borevich-Shafarevich), Cohn's book is a fine read."

Thursday, July 3, 2014

Core Mathematics: Arrays

Filed under: General — m759 @ 11:00 am

Mathematics vulgarizer Keith Devlin on July 1
posted an essay on Common Core math education.

His essay was based on a New York Times story from June 29,
Math Under Common Core Has Even Parents Stumbling.”

An image from that story:

The Times  gave no source, other than the photographer’s name,
for the above image.  Devlin said,

“… the image of a Common Core math worksheet
the Times  chose to illustrate its story showed
a very sensible, and deep use of dot diagrams,
to understand structure in arithmetic.”  

Devlin seems ignorant of the fact that there is
no such thing as a “Common Core math worksheet.”
The Core is a set of standards without  worksheets
(one of its failings).

Neither the Times  nor whoever filled out the worksheet
nor Devlin seemed to grasp that the image the Times  used
shows some multiplication word problems that are more
advanced than the topic that Devlin called the
“deep use of dot diagrams to understand structure in arithmetic.”

This Core topic is as follows:

For some worksheets that are  (purportedly) relevant, see,
for instance…

http://search.theeducationcenter.com/search/
_Common_Core_Label-2.OA.C.4–keywords-math_worksheets,
in particular the worksheet
http://www.theeducationcenter.com/editorial_content/multipli-city:

Some other exercises said to be related to standard 2.OA.C.4:

http://www.ixl.com/standards/
common-core/math/grade-2

The Common Core of course fails to provide materials for parents
that are easily findable on the Web and that give relevant background
for the above second-grade topic.  It leaves this crucial task up to
individual states and school districts, as well as to private enterprise.
This, and not the parents’ ignorance described in  Devlin’s snide remarks,
accounts for the frustration that the Times  story describes.

Sunday, March 9, 2014

The Story Creeps Up

Filed under: General,Geometry — Tags: , , — m759 @ 11:01 pm

For Women’s History Month —

Conclusion of “The Storyteller,” a story
by Cynthia Zarin about author Madeleine L’Engle—

See also the exercise on the Miracle Octad Generator (MOG) at the end of
the previous post, and remarks on the MOG by Emily Jennings (non -fiction)
on All Saints’ Day, 2012 (the date the L’Engle quote was posted here).

Hesse’s Table

Filed under: General,Geometry — Tags: , , , — m759 @ 9:00 pm

From “Quartic Curves and Their Bitangents,” by
Daniel Plaumann, Bernd Sturmfels, and Cynthia Vinzant,
arXiv:1008.4104v2  [math.AG] 10 Jan 2011 —

The table mentioned (from 1855) is…

Exercise: Discuss the relationship, if any, to
the Miracle Octad Generator of R. T. Curtis.

Thursday, December 5, 2013

Blackboard Jungle

Filed under: General,Geometry — Tags: , , — m759 @ 11:07 am

Continued from Field of Dreams, Jan. 20, 2013.

IMAGE- Richard Kiley in 'Blackboard Jungle,' with grids and broken records

That post mentioned the March 2011 AMS Notices ,
an issue on mathematics education.

In that issue was an interview with Abel Prize winner
John Tate done in Oslo on May 25, 2010, the day
he was awarded the prize. From the interview—

Research Contributions

Raussen and Skau: This brings us to the next
topic: Your Ph.D. thesis from 1950, when you were
twenty-five years old. It has been extensively cited
in the literature under the sobriquet “Tate’s thesis”.
Several mathematicians have described your thesis
as unsurpassable in conciseness and lucidity and as
representing a watershed in the study of number
fields. Could you tell us what was so novel and fruitful
in your thesis?

Tate: Well, first of all, it was not a new result, except
perhaps for some local aspects. The big global
theorem had been proved around 1920 by the
great German mathematician Erich Hecke, namely
​the fact that all L -functions of number fields,
abelian -functions, generalizations of Dirichlet’s
L -functions, have an analytic continuation
throughout the plane with a functional equation
of the expected type. In the course of proving
it Hecke saw that his proof even applied to a new
kind of L -function, the so-called L -functions with
Grössencharacter. Artin suggested to me that one
might prove Hecke’s theorem using abstract
harmonic analysis on what is now called the adele
ring, treating all places of the field equally, instead
of using classical Fourier analysis at the archimedian 
places and finite Fourier analysis with congruences 
at the p -adic places as Hecke had done. I think I did
a good job —it might even have been lucid and
concise!—but in a way it was just a wonderful 
exercise to carry out this idea. And it was also in the
air. So often there is a time in mathematics for 
something to be done. My thesis is an example. 
Iwasawa would have done it had I not.

[For a different perspective on the highlighted areas of
mathematics, see recent remarks by Edward Frenkel.]

"So often there is a time in mathematics for something to be done."

— John Tate in Oslo on May 25, 2010.

See also this journal on May 25, 2010, as well as
Galois Groups and Harmonic Analysis on Nov. 24, 2013.

Friday, November 1, 2013

Cameron’s Group Theory Notes

Filed under: General,Geometry — Tags: , — m759 @ 7:00 am

In "Notes on Finite Group Theory"
by Peter J. Cameron (October 2013),
http://www.maths.qmul.ac.uk/~pjc/notes/gt.pdf,
some parts are particularly related to the mathematics of
the 4×4 square (viewable in various ways as four quartets)—

  • Definition 1.3.1, Group actions, and example on partitions of a 4-set, p. 19.
  • Exercise 1.1, The group of Fano-plane symmetries, p. 35.
  • Exercise 2.17, The group of the empty set and the 15 two-subsets of a six-set, p. 66.
  • Section 3.1.2, The holomorph of a group, p. 70.
  • Exercise 3.7, The groups A8 and AGL(4,2), p. 78.

Cameron is the author of Parallelisms of Complete Designs ,
a book notable in part for its chapter epigraphs from T.S. Eliot's
Four Quartets . These epigraphs, if not the text proper, seem
appropriate for All Saints' Day.

But note also Log24 posts tagged Not Theology.

Wednesday, May 1, 2013

For Law Day

Filed under: General — m759 @ 12:00 pm

Harvard Gazette , March 4th, 2013:

"Winfrey will speak on May 30 during Commencement day’s
Afternoon Exercises, which serve as the annual meeting of
the Harvard Alumni Association. The exercises will take place
in the Tercentenary Theatre of Harvard Yard,
between Memorial Church and Widener Library."

On the 1977 Octavia Butler novel Mind of My Mind :

"The first chapter in a history that Butler has already taken up
at a much later stage in Patternmaster  (1976).
Mind of My Mind  begins with Doro, a ruthless mutant
as old as the pyramids who has spent the last 4,000 years
trying to breed a race in his own image. The culminating
experiment is his daughter Mary. But, to Doro's astonishment,
Mary's first instinct on attaining her full powers is to begin
building a mental community— a Pattern— out of the
wretched thousands of Doro's half-telepathic failures
and partial successes. Despite some ragged moments,
Butler is clearly on to a promising vein— something like
Zenna Henderson's 'People' stories without their
saccharine silliness. There's a lot of intrinsic energy in the
Pattern idea, and one wants to see where this erratic, gifted
storyteller will pick it up next."

Kirkus Reviews , Vol. XLV, No. 8 (1977), p. 453.

See this journal on Butler's dies natalis , the feast of St. Matthias, 2006.

Those who prefer Eastern approaches to religion may consult
Robert Thurman and his daughter Uma.

"Oprah, Uma. Uma, Oprah." — David Letterman

Tuesday, April 30, 2013

Projective Analysis

Filed under: General,Geometry — m759 @ 8:00 pm

A Nested Sequence of Complete N-points and Their Sections

The complete space 6-point
(6 points in general position in space,
5 lines on each point, and 15 lines, 2 points on each)
has as a section 
the large Desargues configuration
(15 points, 4 lines on each, and 20 lines, 3 points on each).

(Veblen and Young, Vol. 1, exercise 11, p. 53)

The large Desargues configuration may in turn be viewed as
the complete space 5-point
(5 points, 4 lines on each, and 10 lines, 2 points on each)
together with its section
the Desargues configuration
(10 points, 3 lines on each, and 10 lines, 3 points on each).

(Veblen and Young, Vol. I, pages 40-42)

The Desargues configuration may in turn be viewed as
the complete space 4-point (tetrahedron)
(4 points, 3 lines on each, and 6 lines, 2 points on each)
together with its section
the complete (plane) 4-side (complete quadrilateral)
(6 points, 2 lines on each, and 4 lines, 3 points on each).

The complete quadrilateral may in turn be viewed as
the complete 3-point (triangle)
(3 points, 2 lines on each, and 3 lines, 2 points on each)
together with its section 
the three-point line
(3 points, 1 line on each, and 1 line, 3 points on the line).

The three-point line may in turn be viewed as
the complete 2-point
(2 points, 1 line on each, and 1 line with 2 points on the line)
together with its section
the complete 1-point
(1 point and 0 lines).

Update of May 1: For related material, see the exercises at the end of Ch. II
in Veblen and Young's Projective Geometry, Vol. I  (Ginn, 1910). For instance:

Sunday, April 28, 2013

The Octad Generator

Filed under: General,Geometry — Tags: , , , , — m759 @ 11:00 pm

… And the history of geometry  
Desargues, Pascal, Brianchon and Galois
in the light of complete n-points in space.

(Rewritten for clarity at about 10 AM ET April 29, with quote from Dowling added.
Updated with a reference to a Veblen and Young exercise (on p. 53) on April 30.)

Veblen and Young, Projective Geometry, Vol. I ,
Ginn and Company, 1910, page 39:

"The Desargues configuration. A very important configuration
is obtained by taking the plane section of a complete space five-point."

Each of figures 14 and 15 above has 15 points and 20 lines.
The Desargues configuration within each figure is denoted by
10 white points and 10 solid lines, with 3 points on each line and
3 lines on each point. Black  points and dashed  lines indicate the
complete space five-point and lines connecting it to the plane section
containing the Desargues configuration.

In a 1915 University of Chicago doctoral thesis, Archibald Henderson
used a complete space six -point to construct a configuration of
15 points and 20 lines in the context not of Desargues '  theorem, but
rather of Brianchon 's theorem and of the Pascal  hexagram.
Henderson's 1915 configuration is, it turns out, isomorphic to that of
the 15 points and 20 lines in the configuration constructed via a
complete space five -point five years earlier by Veblen and Young.
(See, in Veblen and Young's 1910 Vol. I, exercise 11, page 53:
"A plane section of a 6-point in space can  be considered as
3 triangles perspective in pairs from 3 collinear points with
corresponding sides meeting in 3 collinear points." This is the
large  Desargues configuration. See Classical Geometry in Light of 
Galois Geometry
.)

For this large  Desargues configuration see April 19.
For Henderson's complete six –point, see The Six-Set (April 23).
That post ends with figures relating the large  Desargues configuration
to the Galois  geometry PG(3,2) that underlies the Curtis
Miracle Octad Generator  and the large Mathieu group M24 —

IMAGE- Geometry of the Six-Set, Steven H. Cullinane, April 23, 2013

See also Note on the MOG Correspondence from April 25, 2013.

That correspondence was also discussed in a note 28 years ago, on this date in 1985.

Saturday, March 2, 2013

Discourse

Filed under: General — Tags: — m759 @ 2:04 pm

(Continued)

"No puzzle has exercised more fascination
upon writers interested in the history of mathematics."

— Sir Thomas Little Heath, quoted by Mark Dominus in
his journal "The Universe of Discourse" on January 22, 2009.

If synchronicity is admitted to the universe of discourse,
a post in this  journal on that same date may be of interest.

Wednesday, December 5, 2012

Arte Programmata*

Filed under: General,Geometry — m759 @ 9:30 pm

The 1976 monograph "Diamond Theory" was an example
of "programmed art" in the sense established by, for
instance, Karl Gerstner. The images were produced 
according to strict rules, and were in this sense 
"programmed," but were drawn by hand.

Now an actual computer program has been written,
based on the Diamond Theory excerpts published
in the Feb. 1977 issue of Computer Graphics and Art
(Vol. 2, No. 1, pp. 5-7), that produces copies of some of
these images (and a few malformed images not  in
Diamond Theory).

See Isaac Gierard's program at GitHub

https://github.com/matthewepler/ReCode_Project/
blob/dda7b23c5ad505340b468d9bd707fd284e6c48bf/
isaac_gierard/StevenHCullinane_DiamondTheory/
StevenHCullinane_DiamondTheory.pde

As the suffix indicates, this program is in the
Processing Development Environment language.

It produces the following sketch:

IMAGE- Sketch programmed by Isaac Gierard to mimic some of the images of 'Diamond Theory' (© 1976 by Steven H. Cullinane).

The rationale for selecting and arranging these particular images is not clear,
and some of the images suffer from defects (exercise: which ones?), but the 
overall effect of the sketch is pleasing.

For some background for the program, see The ReCode Project.

It is good to learn that the Processing language is well-adapted to making the 
images in such sketches. The overall structure of the sketch gives, however,
no clue to the underlying theory  in "Diamond Theory."

For some related remarks, see Theory (Sept. 30, 2012).

* For the title, see Darko Fritz, "Notions of the Program in 1960s Art."

Tuesday, July 10, 2012

Euclid vs. Galois

Filed under: General,Geometry — Tags: , — m759 @ 11:01 am

(Continued)

Euclidean square and triangle

Galois square and triangle

Background—

This journal on the date of Hilton Kramer's death,
The Galois Tesseract, and The Purloined Diamond.

Sunday, April 1, 2012

The Palpatine Dimension

Filed under: General,Geometry — Tags: , — m759 @ 9:00 am

A physics quote relayed at Peter Woit's weblog today—

"The relation between 4D N=4 SYM and the 6D (2, 0) theory
is just like that between Darth Vader and the Emperor.
You see Darth Vader and you think 'Isn’t he just great?
How can anyone be greater than that? No way.'
Then you meet the Emperor."

— Arkani-Hamed

Some related material from this  weblog—

(See Big Apple and Columbia Film Theory)

http://www.log24.com/log/pix12/120108-Space_Time_Penrose_Hawking.jpg

The Meno Embedding:

Plato's Diamond embedded in The Matrix

Some related material from the Web—

IMAGE- The Penrose diamond and the Klein quadric

See also uses of the word triality  in mathematics. For instance…

A discussion of triality by Edward Witten

Triality is in some sense the last of the exceptional isomorphisms,
and the role of triality for n = 6  thus makes it plausible that n = 6
is the maximum dimension for superconformal symmetry,
though I will not give a proof here.

— "Conformal Field Theory in Four and Six Dimensions"

and a discussion by Peter J. Cameron

There are exactly two non-isomorphic ways
to partition the 4-subsets of a 9-set
into nine copies of AG( 3,2).
Both admit 2-transitive groups.

— "The Klein Quadric and Triality"

Exercise: Is Witten's triality related to Cameron's?
(For some historical background, see the triality  link from above
and Cameron's Klein Correspondence and Triality.)

Cameron applies his  triality to the pure geometry of a 9-set.
For a 9-set viewed in the context of physics, see A Beginning

From MIT Commencement Day, 2011—

A symbol related to Apollo, to nine, and to "nothing"

A minimalist favicon—

IMAGE- Generic 3x3 square as favicon

This miniature 3×3 square— http://log24.com/log/pix11A/110518-3x3favicon.ico — may, if one likes,
be viewed as the "nothing" present at the Creation. 
See Feb. 19, 2011, and Jim Holt on physics.

Happy April 1.

Sunday, January 22, 2012

The Presbyterian Exorcist

Filed under: General — Tags: , — m759 @ 9:26 am

(Backstory— Presbyterian in this journal)

Princeton University Press on a book it will publish in March—

Circles Disturbed  brings together important thinkers in mathematics, history, and philosophy to explore the relationship between mathematics and narrative. The book's title recalls the last words of the great Greek mathematician Archimedes before he was slain by a Roman soldier–"Don't disturb my circles"–words that seem to refer to two radically different concerns: that of the practical person living in the concrete world of reality, and that of the theoretician lost in a world of abstraction. Stories and theorems are, in a sense, the natural languages of these two worlds–stories representing the way we act and interact, and theorems giving us pure thought, distilled from the hustle and bustle of reality. Yet, though the voices of stories and theorems seem totally different, they share profound connections and similarities.

Exercise— Discuss the above paragraph's vulgarity.

Discuss also the more robust vulgarity of Marvel Entertainment

Context— "Marvel" in this journal, and The Cosmic Cube.

Monday, January 16, 2012

Mapping Problem

Filed under: General,Geometry — Tags: , , — m759 @ 5:10 pm

Thursday's post Triangles Are Square posed the problem of
finding "natural" maps from the 16 subsquares of a 4×4 square
to the 16 equilateral subtriangles of an edge-4 equilateral triangle.

http://www.log24.com/log/pix12/120116-SquareAndTriangle.jpg

Here is a trial solution of the inverse problem—

http://www.log24.com/log/pix12/120116-trisquare-map-500w.jpg

(Click for larger version.)

Exercise— Devise a test for "naturality" of
such mappings and apply it to the above.

Friday, September 16, 2011

Icons

Filed under: General,Geometry — Tags: — m759 @ 12:00 am

Background: Jung's Aion in this journal discusses this
figure from finite geometry's diamond theorem

http://www.log24.com/log/pix11B/110915-FourDiamondsIcon.gif

Fig. A

This resembles a figure that served Jung
as a schema of the Self

http://www.log24.com/log/pix11B/110915-Jung-FourDiamonds.gif

Fig. B

Fig. A, with color variations, serves as the core
of many automatically generated Identicons
a different sort of self-symbol.

Examples from Sept. 6 at MathOverflow

http://www.log24.com/log/pix11B/110915-ChuangGravatar.png     http://www.log24.com/log/pix11B/110915-JacobLurieGravatar.png

A user wanting to custom-tailor his self-symbol should consider
the following from the identicon service Gravatar

1. User Submissions.  " you hereby do and shall grant to Automattic a worldwide, perpetual, irrevocable, royalty-free and fully-paid, transferable (including rights to sublicense) right to perform the Services (e.g., to use, modify, reproduce, distribute, prepare derivative works of, display, perform, and otherwise fully exercise and exploit all intellectual property, publicity, and moral rights with respect to any User Submissions, and to allow others to do so)."

Sounds rather Faustian.

Monday, July 11, 2011

And/Or Problem

Filed under: General,Geometry — Tags: — m759 @ 11:59 pm

"It was the simultaneous emergence
and mutual determination
of probability and logic
that von Neumann found intriguing
and not at all well understood."

Miklós Rédei

Context:

Update of 7 AM ET July 12, 2011—

Freeman Dyson on John von Neumann's
Sept. 2, 1954, address to the International
Congress of Mathematicians on
"Unsolved Problems in Mathematics"—

                                     …."The hall was packed with
mathematicians, all expecting to hear a brilliant
lecture worthy of such a historic occasion. The
lecture was a huge disappointment. Von Neumann
had probably agreed several years earlier to give
a lecture about unsolved problems and had then
forgotten about it. Being busy with many other
things, he had neglected to prepare the lecture.
Then, at the last moment, when he remembered
that he had to travel to Amsterdam and say something
about mathematics, he pulled an old lecture
from the 1930s out of a drawer and dusted it off.
The lecture was about rings of operators, a subject
that was new and fashionable in the 1930s. Nothing
about unsolved problems.
Nothing about the
future."

Notices of the American Mathematical Society ,
February 2009, page 220

For a different account, see Giovanni Valente's
2009 PhD thesis from the University of Maryland,
Chapter 2, "John von Neumann's Mathematical
'Utopia' in Quantum Theory"—

"During his lecture von Neumann discussed operator theory and its con-
nections with quantum mechanics and noncommutative probability theory,
pinpointing a number of unsolved problems. In his view geometry was so tied
to logic that he ultimately outlined a logical interpretation of quantum prob-
abilities. The core idea of his program is that probability is invariant under
the symmetries of the logical structure of the theory. This is tantamount to
a formal calculus in which logic and probability arise simultaneously. The
problem that exercised von Neumann then was to construct a geometrical
characterization of the whole theory of logic, probability and quantum me-
chanics, which could be derived from a suitable set of axioms…. As he
himself finally admitted, he never managed to set down the sought-after
axiomatic formulation in a way that he felt satisfactory."

Tuesday, June 28, 2011

Signature*

Filed under: General — m759 @ 2:45 am

"He gazed out of the window hoping that somehow everything could make sense to him."

— "Passing in Silence," by Oliver Humpage

"You gotta be true to your code." —Sinatra

Exercise: Trace a path from the June 27 NY Lottery numbers
to the above two quotations.  Hint: See Cuernavaca and
Pilgrim's Progress  in TIME Magazine, May 3, 1948.

http://www.log24.com/log/pix11A/110628-CBS-5348.jpg

For some further background, click on the CBS quote above.
I still prefer, as I did in 1948, less  up-to-the-minute developments.

* The title refers to the phrase "the artist's signature."

Friday, June 17, 2011

Bloomsday Lottery

Filed under: General — m759 @ 4:09 am

http://www.log24.com/log/pix11A/110616-NYlottery.jpg

This morning's exercise in lottery hermeneutics is unusually difficult.

Yesterday was Bloomsday (the date described in
James Joyce's Ulysses ) and the New York Lottery numbers were…

Midday  numbers:  3-digit 181, 4-digit 9219.

Evening numbers: 3-digit 478, 4-digit 6449.

For 181 and 9219, see the following—

"With respect to every event, we must ask
 which element has been subjected directly to change."
— Ferdinand de Saussure, Course in General Linguistics
   (New York, The Philosophical Library, Inc., 1959), page 181

That Saussure page number was referenced in the following thesis
on James Joyce's other major novel, Finnegans Wake

http://www.log24.com/log/pix11A/110617-Masterarbeit9219.jpg

The thesis is from the University of Vienna (Universität Wien ).

http://www.log24.com/log/pix11A/110617-UniversitatWienSeal.jpg

The word Wien , in the derived form denoting an inhabitant of that city,
figured prominently in yesterday's news.

As for the evening numbers—

478 perhaps signifies the year 478 BC,
cited in Lawrence Durrell's Sicilian Carousel  as the year
the ruler Gelon died.

For the evening 6449, note that the poem by Wallace Stevens quoted
here on June 15 in A for Anastasios deals with "the river of rivers"…
perhaps signifying time.

Interpreting 6449 chronologically yields 6/4/49.

The film artist  John Huston, discussed in an essay from that date,
might appreciate the representation of the ancient Sicilian
river god Gelas as a man-headed bull on a coin from
around the year 478 BC.

For some perceptive remarks about Durrell, see the
article by Nigel Dennis in LIFE magazine's Nov. 21, 1960
issue (with cover noting Kennedy's victory in that year's
presidential election).

All of the above may be viewed as an approach to the aesthetic
problem posed by Dennis in yesterday's Bloomsday post

"The problem that arises with this sort of writing is
one of form, i.e. , how to make one strong parcel
out of so many differently shaped commodities,
how to impose method on what would otherwise
be madness."

"The world has gone mad today…." — Cole Porter

For some related remarks, see page 161 of
Joyce's Catholic Comedy of Language
*
by Beryl Schlossman (U. of Wisconsin Press, 1985)
and James Joyce in the final pages of The Left Hand of God
by Adolf Holl.

* Update of July 6, 2011—
This title is a correction from the previous title
given here, Moral Language  by Mary Gore Forrester.
Google Books had Schlossman's content previewed
under Forrester's title.

Friday, June 3, 2011

First Class

Filed under: General — Tags: — m759 @ 6:15 pm

It's a very ancient saying, but a true and honest thought,
that if you become a teacher, by your pupils you'll be taught
.”

Related material—

* Spiritual Exercises  of Ignatius Loyola—

Composition of Place

It should be noted here that for contemplation or meditation about
visible things…  the ‘composition’ will consist in seeing through the
gaze of the imagination the material place where the object I want
to contemplate is situated.

West Side Memories  (an off-off-off-off Broadway production)—

http://www.log24.com/log/pix11A/110603-CompositionOfPlace-Sm.jpg

Tuesday, May 10, 2011

Groups Acting

Filed under: General,Geometry — Tags: , , , — m759 @ 10:10 am

The LA Times  on last weekend's film "Thor"—

"… the film… attempts to bridge director Kenneth Branagh's high-minded Shakespearean intentions with Marvel Entertainment's bottom-line-oriented need to crank out entertainment product."

Those averse to Nordic religion may contemplate a different approach to entertainment (such as Taymor's recent approach to Spider-Man).

A high-minded— if not Shakespearean— non-Nordic approach to groups acting—

"What was wrong? I had taken almost four semesters of algebra in college. I had read every page of Herstein, tried every exercise. Somehow, a message had been lost on me. Groups act . The elements of a group do not have to just sit there, abstract and implacable; they can do  things, they can 'produce changes.' In particular, groups arise naturally as the symmetries of a set with structure. And if a group is given abstractly, such as the fundamental group of a simplical complex or a presentation in terms of generators and relators, then it might be a good idea to find something for the group to act on, such as the universal covering space or a graph."

— Thomas W. Tucker, review of Lyndon's Groups and Geometry  in The American Mathematical Monthly , Vol. 94, No. 4 (April 1987), pp. 392-394

"Groups act "… For some examples, see

Related entertainment—

High-minded— Many Dimensions

Not so high-minded— The Cosmic Cube

http://www.log24.com/log/pix11A/110509-SpideySuperStories39Sm.jpg

One way of blending high and low—

The high-minded Charles Williams tells a story
in his novel Many Dimensions about a cosmically
significant cube inscribed with the Tetragrammaton—
the name, in Hebrew, of God.

The following figure can be interpreted as
the Hebrew letter Aleph inscribed in a 3×3 square—

http://www.log24.com/log/pix11A/110510-GaloisAleph.GIF

The above illustration is from undated software by Ed Pegg Jr.

For mathematical background, see a 1985 note, "Visualizing GL(2,p)."

For entertainment purposes, that note can be generalized from square to cube
(as Pegg does with his "GL(3,3)" software button).

For the Nordic-averse, some background on the Hebrew connection—

Friday, March 18, 2011

Defining Configurations*

Filed under: General,Geometry — Tags: , — m759 @ 7:00 pm

The On-Line Encyclopedia of Integer Sequences has an article titled "Number of combinatorial configurations of type (n_3)," by N.J.A. Sloane and D. Glynn.

From that article:

  • DEFINITION: A combinatorial configuration of type (n_3) consists of an (abstract) set of n points together with a set of n triples of points, called lines, such that each point belongs to 3 lines and each line contains 3 points.
  • EXAMPLE: The unique (8_3) configuration consists of the triples 125, 148, 167, 236, 278, 347, 358, 456.

The following corrects the word "unique" in the example.

http://www.log24.com/log/pix11/110320-MoebiusKantorConfig500w.jpg

* This post corrects an earlier post, also numbered 14660 and dated 7 PM March 18, 2011, that was in error.
   The correction was made at about 11:50 AM on March 20, 2011.

_____________________________________________________________

Update of March 21

The problem here is of course with the definition. Sloane and Glynn failed to include in their definition a condition that is common in other definitions of configurations, even abstract or purely "combinatorial" configurations. See, for instance, Configurations of Points and Lines , by Branko Grunbaum (American Mathematical Society, 2009), p. 17—

In the most general sense we shall consider combinatorial (or abstract) configurations; we shall use the term set-configurations as well. In this setting "points" are interpreted as any symbols (usually letters or integers), and "lines" are families of such symbols; "incidence" means that a "point" is an element of a "line". It follows that combinatorial configurations are special kinds of general incidence structures. Occasionally, in order to simplify and clarify the language, for "points" we shall use the term marks, and for "lines" we shall use blocks. The main property of geometric configurations that is preserved in the generalization to set-configurations (and that characterizes such configurations) is that two marks are incident with at most one block, and two blocks with at most one mark.

Whether or not omitting this "at most one" condition from the definition is aesthetically the best choice, it dramatically changes the number  of configurations in the resulting theory, as the above (8_3) examples show.

Update of March 22 (itself updated on March 25)

For further background on configurations, see Dolgachev—

http://www.log24.com/log/pix11/110322-DolgachevIntro.gif

Note that the two examples Dolgachev mentions here, with 16 points and 9 points, are not unrelated to the geometry of 4×4 and 3×3 square arrays. For the Kummer and related 16-point configurations, see section 10.3, "The Three Biplanes of Order 4," in Burkard Polster's A Geometrical Picture Book  (Springer, 1998). See also the 4×4 array described by Gordon Royle in an undated web page and in 1980 by Assmus and Sardi. For the Hesse configuration, see (for instance) the passage from Coxeter quoted in Quaternions in an Affine Galois Plane.

Update of March 27

See the above link to the (16,6) 4×4 array and the (16,6) exercises using this array in R.D. Carmichael's classic Introduction to the Theory of Groups of Finite Order  (1937), pp. 42-43. For a connection of this sort of 4×4 geometry to the geometry of the diamond theorem, read "The 2-subsets of a 6-set are the points of a PG(3,2)" (a note from 1986) in light of R.W.H.T. Hudson's 1905 classic Kummer's Quartic Surface , pages 8-9, 16-17, 44-45, 76-77, 78-79, and 80.

Friday, February 25, 2011

Diamond Theorem Exposition

Filed under: General,Geometry — m759 @ 11:00 pm

"THE DIAMOND THEOREM AND QUILT PATTERNS
Victoria Blumen, Mathematics, Junior, Benedictine University
Tim Comar, Benedictine University
Mathematics
Secondary Source Research
 
Let D be a 4 by 4 block quilt shape, where each of the 16 square blocks is consists of [sic ] two triangles, one of which is colored red and the other of which is colored blue.  Let G: D -> D_g be a mapping of D that interchanges a pair of columns, rows, or quadrants of D.  The diamond theorem states that G(D) = D_g has either ordinary or color-interchange symmetry.  In this talk, we will prove the diamond theorem and explore symmetries of quilt patterns of the form G(D)."

Exercise Correct the above statement of the theorem.

Background— This is from a Google search result at about 10:55 PM ET Feb. 25, 2011—

[DOC] THE DIAMOND THEOREM AND QUILT PATTERNS – acca.elmhurst.edu
File Format: Microsoft Word – 14 hours ago –
Let G: D -> D_g be a mapping of D that interchanges a pair of columns, rows, or quadrants of D. The diamond theorem states that G(D) = D_g has either
acca.elmhurst.edu/…/victoria_blumen9607_
THE%20DIAMOND%20THEOREM%20AND%20QUILT%20PATTERNS…

The document is from a list of mathematics abstracts for the annual student symposium of the ACCA (Associated Colleges of the Chicago Area) held on April 10, 2010.

Update of Feb. 26For a related remark quoted here  on the date of the student symposium, see Geometry for Generations.

Monday, December 27, 2010

Church Diamond

Filed under: General,Geometry — Tags: — m759 @ 3:09 pm

IMAGE- The diamond property

Also known, roughly speaking, as confluence  or the Church-Rosser property.

From “NYU Lambda Seminar, Week 2” —

[See also the parent page Seminar in Semantics / Philosophy of Language or:
What Philosophers and Linguists Can Learn From Theoretical Computer Science But Didn’t Know To Ask)
]

A computational system is said to be confluent, or to have the Church-Rosser or diamond property, if, whenever there are multiple possible evaluation paths, those that terminate always terminate in the same value. In such a system, the choice of which sub-expressions to evaluate first will only matter if some of them but not others might lead down a non-terminating path.

The untyped lambda calculus is confluent. So long as a computation terminates, it always terminates in the same way. It doesn’t matter which order the sub-expressions are evaluated in.

A computational system is said to be strongly normalizing if every permitted evaluation path is guaranteed to terminate. The untyped lambda calculus is not strongly normalizing: ω ω doesn’t terminate by any evaluation path; and (\x. y) (ω ω) terminates only by some evaluation paths but not by others.

But the untyped lambda calculus enjoys some compensation for this weakness. It’s Turing complete! It can represent any computation we know how to describe. (That’s the cash value of being Turing complete, not the rigorous definition. There is a rigorous definition. However, we don’t know how to rigorously define “any computation we know how to describe.”) And in fact, it’s been proven that you can’t have both. If a computational system is Turing complete, it cannot be strongly normalizing.

There is no connection, apart from the common reference to an elementary geometric shape, between the use of “diamond” in the above Church-Rosser sense and the use of “diamond” in the mathematics of (Cullinane’s) Diamond Theory.

Any attempt to establish such a connection would, it seems, lead quickly into logically dubious territory.

Nevertheless, in the synchronistic spirit of Carl Jung and Arthur Koestler, here are some links to such a territory —

 Link One — “Insane Symmetry”  (Click image for further details)—

http://www.log24.com/log/pix10B/101227-InsaneSymmetry.jpg

See also the quilt symmetry in this  journal on Christmas Day.

Link Two — Divine Symmetry

(George Steiner on the Name in this journal on Dec. 31 last year (“All about Eve“)) —

“The links are direct between the tautology out of the Burning Bush, that ‘I am’ which accords to language the privilege of phrasing the identity of God, on the one hand, and the presumptions of concordance, of equivalence, of translatability, which, though imperfect, empower our dictionaries, our syntax, our rhetoric, on the other. That ‘I am’ has, as it were, at an overwhelming distance, informed all predication. It has spanned the arc between noun and verb, a leap primary to creation and the exercise of creative consciousness in metaphor. Where that fire in the branches has gone out or has been exposed as an optical illusion, the textuality of the world, the agency of the Logos in logic—be it Mosaic, Heraclitean, or Johannine—becomes ‘a dead letter.'”

George Steiner, Grammars of Creation

(See also, from Hanukkah this year,  A Geometric Merkabah and The Dreidel is Cast.)

Link Three – Spanning the Arc —

Part A — Architect Louis Sullivan on “span” (see also Kindergarten at Stonehenge)

Part B — “Span” in category theory at nLab —

http://www.log24.com/log/pix10B/101227-nLabSpanImage.jpg

Also from nLab — Completing Spans to Diamonds

“It is often interesting whether a given span in some partial ordered set can be completed into a diamond. The property of a collection of spans to consist of spans which are expandable into diamonds is very useful in the theory of rewriting systems and producing normal forms in algebra. There are classical results e.g. Newman’s diamond lemma, Širšov-Bergman’s diamond lemma (Širšov is also sometimes spelled as Shirshov), and Church-Rosser theorem (and the corresponding Church-Rosser confluence property).”

The concepts in this last paragraph may or may not have influenced the diamond theory of Rudolf Kaehr (apparently dating from 2007).

They certainly have nothing to do with the Diamond Theory of Steven H. Cullinane (dating from 1976).

For more on what the above San Francisco art curator is pleased to call “insane symmetry,” see this journal on Christmas Day.

For related philosophical lucubrations (more in the spirit of Kaehr than of Steiner), see the New York Times  “The Stone” essay “Span: A Remembrance,” from December 22—

“To understand ourselves well,” [architect Louis] Sullivan writes, “we must arrive first at a simple basis: then build up from it.”

Around 300 BC, Euclid arrived at this: “A point is that which has no part. A line is breadthless length.”

See also the link from Christmas Day to remarks on Euclid and “architectonic” in Mere Geometry.

Wednesday, September 8, 2010

Grand Design

Filed under: General — m759 @ 2:22 am

From Harvard's 2010 Phi Beta Kappa ceremony

Think of all the history you’ve read. It started somewhere.
It started at absolute zero, is what you thought.
Just because you couldn’t know what came before.
But imagine: something did.

"To help the graduates find rightness, two addresses are at the heart of the exercises ceremony.
 One is by a poet, who reads a work written for the occasion.
 The other is by an 'orator,' a guest invited to offer timely discourse."

From this morning's New York Times

http://www.log24.com/log/pix10B/100908-ThursdayDeath.jpg

Related material—

Immediately following Inspector Pine in this morning's Times  obituary list
is Virginia B. Smith, a former president of Vassar College. Smith died at 87 on August 27.

From her obituary—

Ms. Smith is survived by her partner of 57 years, Florence Oaks.

Tuesday, August 17, 2010

Riff Design

Filed under: General — Tags: , — m759 @ 5:09 am

From yesterday

Call and Response

“One would call out, in the standardized abbreviations of their science, motifs or initial bars of classical compositions, whereupon the other had to respond with the continuation of the piece, or better still with a higher or lower voice, a contrasting theme, and so forth. It was an exercise in memory and improvisation….”

The Glass Bead Game

Today’s New York Times  has an obituary for Bernard Knox, classics professor. Knox died on July 22. On that date this journal happened to have a post, “Soul Riff,” featuring a professor— shown below. Click on the professor for a very relevant classical quotation.

The Soul Riff  post also contained the above secondary title—

Call and Response

Doonesbury 2/29/08-- Assignment: Identify Sources

For a response from the next day,
March 1, click on the professor
.

Monday, August 16, 2010

Utopia 14

Filed under: General — Tags: , — m759 @ 4:16 am

The following, from Wikipedia, is an image of Utopia 14, the 1954 paperback reissue of Kurt Vonnegut’s 1952 novel Player Piano.

http://www.log24.com/log/pix10B/100816-Utopia14-Vonnegut.jpg

Commentary from Wikipedia

“A player piano is a modified piano that ‘plays itself.’ The piano keys move according to a pattern of holes punched in an unwinding scroll…. Like its counterpart, a player piano can be played by hand as well. When a scroll is run through the ghost-operated instrument, the movement of its keys produce the illusion that an invisible performer is playing the instrument.”

See also last night’s “The Game“—

“One would call out, in the standardized abbreviations of their science, motifs or initial bars of classical compositions, whereupon the other had to respond with the continuation of the piece, or better still with a higher or lower voice, a contrasting theme, and so forth. It was an exercise in memory and improvisation….”

— as well as Vonnegut in this journal yesterday and the following from the August 14 post Iconic Notation

A question from Ivan Illich
(founder of CIDOC, the Center for Intercultural Documentation,
in Cuernavaca, Mexico)—

Who can be served by bridges to nowhere?

For more about nowhere, see Utopia.

For more about Cuernavaca and ghosts, see a recurring motif in this journal.

Sunday, August 15, 2010

The Game

Filed under: General — Tags: , , — m759 @ 11:07 pm
'Magister Ludi,' or 'The Glass Bead Game,' by Hermann Hesse

We shall now give a brief summary of the beginnings of the Glass Bead Game. It appears to have arisen simultaneously in Germany and in England. In both countries, moreover, it was originally a kind of exercise employed by those small groups of musicologists and musicians who worked and studied in the new seminaries of musical theory. If we compare the original state of the Game with its subsequent developments and its present form, it is much like comparing a musical score of the period before 1500, with its primitive notes and absence of bar lines, with an eighteenth-century score, let alone with one from the nineteenth with its confusing excess of symbols for dynamics, tempi, phrasing, and so on, which often made the printing of such scores a complex technical problem.

The Game was at first nothing more than a witty method for developing memory and ingenuity among students and musicians. And as we have said, it was played both in England and Germany before it was ‘invented’ here in the Musical Academy of Cologne, and was given the name it bears to this day, after so many generations, although it has long ceased to have anything to do with glass beads.

The inventor, Bastian Perrot of Calw, a rather eccentric but clever, sociable, and humane musicologist, used glass beads instead of letters, numerals, notes, or other graphic symbols. Perrot, who incidentally has also bequeathed to us a treatise on the Apogee and Decline of Counterpoint, found that the pupils at the Cologne Seminary had a rather elaborate game they used to play. One would call out, in the standardized abbreviations of their science, motifs or initial bars of classical compositions, whereupon the other had to respond with the continuation of the piece, or better still with a higher or lower voice, a contrasting theme, and so forth. It was an exercise in memory and improvisation quite similar to the sort of thing probably in vogue among ardent pupils of counterpoint in the days of Schütz, Pachelbel, and Bach — although it would then not have been done in theoretical formulas, but in practice on the cembalo, lute, or flute, or with the voice.

Bastian Perrot in all probability was a member of the Journeyers to the East. He was partial to handicrafts and had himself built several pianos and clavichords in the ancient style. Legend has it that he was adept at playing the violin in the old way, forgotten since 1800, with a high-arched bow and hand-regulated tension of the bow hairs. Given these interests, it was perhaps only natural that he should have constructed a frame, modeled on a child’s abacus, a frame with several dozen wires on which could be strung glass beads of various sizes, shapes, and colors. The wires corresponded to the lines of the musical staff, the beads to the time-values of the notes, and so on. In this way he could represent with beads musical quotations or invented themes, could alter, transpose, and develop them, change them and set them in counterpoint to one another. In technical terms this was a mere plaything, but the pupils liked it; it was imitated and became fashionable in England too. For a time the game of musical exercises was played in this charmingly primitive manner. And as is so often the case, an enduring and significant institution received its name from a passing and incidental circumstance. For what later evolved out of that students’ sport and Perrot’s bead-strung wires bears to this day the name by which it became popularly known, the Glass Bead Game.

Hermann Hesse

“For although in a certain sense and for light-minded persons non-existent things can be more easily and irresponsibly represented in words than existing things, for the serious and conscientious historian it is just the reverse. Nothing is harder, yet nothing is more necessary, than to speak of certain things whose existence is neither demonstrable nor probable. The very fact that serious and conscientious men treat them as existing things brings them a step closer to existence and to the possibility of being born.”

— “Albertus Secundus,” epigraph to The Glass Bead Game

From DownloadThat.com

(Click to enlarge.)

http://www.log24.com/log/pix10B/100815-ThePaletteSm.jpg

Tuesday, July 6, 2010

Window, continued

“Simplicity, simplicity, simplicity!
I say, let your affairs be as two or three,
and not a hundred or a thousand;
instead of a million count half a dozen,
and keep your accounts on your thumb-nail.”
— Henry David Thoreau, Walden

This quotation is the epigraph to
Section 1.1 of Alexandre V. Borovik’s
Mathematics Under the Microscope:
Notes on Cognitive Aspects of Mathematical Practice
(American Mathematical Society,
Jan. 15, 2010, 317 pages).

From Peter J. Cameron’s review notes for
his new course in group theory

http://www.log24.com/log/pix10A/100705-CameronExample.jpg

From Log24 on June 24

Geometry Simplified

Image-- The Four-Point Plane: A Finite Affine Space
(an affine  space with subsquares as points
and sets  of subsquares as hyperplanes)

Image-- The Three-Point Line: A Finite Projective Space
(a projective  space with, as points, sets
of line segments that separate subsquares)

Exercise

Show that the above geometry is a model
for the algebra discussed by Cameron.

Sunday, February 14, 2010

Sunday School

Filed under: General,Geometry — m759 @ 9:00 am

"Simplify, simplify." — Henry David Thoreau

"Because of their truly fundamental role in mathematics, even the simplest diagrams concerning finite reflection groups (or finite mirror systems, or root systems– the languages are equivalent) have interpretations of cosmological proportions."

Alexandre Borovik, 2010 (See previous entry.)

Exercise: Discuss Borovik's remark
that "the languages are equivalent"
in light of the web page

http://www.log24.com/log/pix10/100214-Cube2x2x2.gif

A Simple Reflection Group
of Order 168
.

Background:

Theorems 15.1 and 15.2 of Borovik's book (1st ed. Nov. 10, 2009)
Mirrors and Reflections: The Geometry of Finite Reflection Groups

15.1 (p. 114): Every finite reflection group is a Coxeter group.

15.2 (p. 114): Every finite Coxeter group is isomorphic to a finite reflection group.

Consider in this context the above simple reflection group of order 168.

(Recall that "…there is only one simple Coxeter group (up to isomorphism); it has order 2…" —A.M. Cohen.)

Wednesday, February 3, 2010

Attitude Adjustment

Filed under: General — Tags: — m759 @ 1:06 pm

"A generation lost in space"
— American Pie

Sperry F3 attitude gyroscope

Sperry F3 attitude gyroscope

Click image for details.

See also the concepts of inner-direction
and other-direction in The Lonely Crowd
by David Riesman et al.  Riesman was,
according to Harvard Square Library,
a contract termination lawyer for
Sperry Gyroscope before turning
to sociology.

EXERCISE — Discuss inner- and
other-direction in education and
in journalism, using the material
in Monday's entry on the
New York Times dunce cap —

http://www.log24.com/log/pix10/100201-Strogatz.jpg


  — contrasted with the webpage
excerpted below —

VisualCommander quaternion display from Princeton Satellite Systems

Thursday, December 31, 2009

All About Eve

Filed under: General — Tags: — m759 @ 9:57 am

NY Times obituaries on New Year's Eve, 2009-- Carlene Hatcher Polite and David Levine

Genesis 3:24
So he drove out the man; and he placed
at the east of the garden of Eden Cherubims,
and a flaming sword which turned every way,
to keep the way of the tree of life.

"The links are direct between the tautology out of the Burning Bush, that 'I am' which accords to language the privilege of phrasing the identity of God, on the one hand, and the presumptions of concordance, of equivalence, of translatability, which, though imperfect, empower our dictionaries, our syntax, our rhetoric, on the other. That 'I am' has, as it were, at an overwhelming distance, informed all predication. It has spanned the arc between noun and verb, a leap primary to creation and the exercise of creative consciousness in metaphor. Where that fire in the branches has gone out or has been exposed as an optical illusion, the textuality of the world, the agency of the Logos in logic—be it Mosaic, Heraclitean, or Johannine—becomes 'a dead letter.'"

George Steiner, Grammars of Creation

Carlene Hatcher Polite–
"Shall I help you?" asked a bass voice.
"If you can," answered a contralto.
"Trace down this tree. Let me show you
men in its stead. Leaf through this bush,
extinguish the burning fire…"
The Flagellants, page 8

"How much story do you want?"
George Balanchine

Wednesday, March 18, 2009

Wednesday March 18, 2009

Filed under: General — Tags: — m759 @ 9:00 am
Gallic Clarity

Yesterday’s entry Deep Structures discussed the “semiotic square,” a device that exemplifies the saying “If you can’t dazzle ’em with brilliance, then baffle ’em with bullshit.”

A search today for what the Marxist critic Fredric Jameson might have meant by saying that the square “is capable of generating at least ten conceivable positions out of a rudimentary binary opposition” leads to two documents of interest.

1. “Theory Pictures as Trails: Diagrams and the Navigation of Theoretical Narratives” (pdf), by J.R. Osborn, Department of Communication, University of California, San Diego (Cognitive Science Online, Vol.3.2, pp.15-44, 2005)

2. “The Semiotic Square” (html), by Louis Hébert (2006), professor, Université du Québec à Rimouski, in Signo (http://www.signosemio.com).

Shown below is Osborn’s picture of the semiotic square:

http://www.log24.com/log/pix09/090318-OsbornTrails.jpg

Osborn’s discussion of the square, though more clear than, say, that of Rosalind Krauss (who reverses the bottom two parts of the square– see Deep Structures), fails. His Appendix A is miserably obscure.

On the brighter side, we have, as a sign that Gallic clarity still exists, the work of Hébert.

Here is how he approaches Jameson’s oft-quoted, but seemingly confused, remark about “ten conceivable positions”–

The Semiotic Square,”
  by Louis Hébert

1. ABSTRACT

The semiotic square, developed by Greimas and Rastier, is a means of refining oppositional analyses by increasing the number of analytical classes stemming from a given opposition from two (life/death, for instance) to four (for example, life, death, life and death (the living dead), and neither life nor death (angels)) to eight or even ten.

2. THEORY

The actantial model, isotopy and the semiotic square are undoubtedly the best-known theoretical propositions that have emerged from the Paris School of semiotics, with Greimas as its central figure. Like the actantial model and the veridictory square, the semiotic square is designed to be both a conceptual network and a visual representation of this network, usually depicted in the form of a “square” (which actually looks like a rectangle!). Courtés defines it as the visual representation of the logical structure of an opposition (cf. Courtés, 1991, 152). The semiotic square is a means of refining oppositional analyses by increasing the number of analytical classes stemming from a given opposition from two (for instance, life/death) to four (for example, life, death, life and death (the living dead), and neither life nor death (angels)) to eight or even ten. Here is an empty semiotic square.

Structure of the semiotic square

   
5. (=1+2) COMPLEX TERM
   
 
1. TERM A  
2. TERM B
 
9. (=1+4)
10. (=2+3)
 
3. TERM NOT-B  
4. TERM NOT-A
 

7. (=1+3)

POSITIVE DEIXIS

8. (=2+4) NEGATIVE DEIXIS
   
   
6. (=3+4) NEUTRAL TERM
   

LEGEND:
The + sign links the terms that are combined to make up a metaterm (a compound term); for example, 5 is the result of combining 1 and 2.

2.1 CONSTITUENT ELEMENTS

The semiotic square entails primarily the following elements (we are steering clear of the constituent relationships of the square: contrariety, contradiction, and complementarity or implication):

1. terms
2. metaterms (compound terms)
3. object(s) (classified on the square)
4. observing subject(s) (who do the classifying)
5. time (of the observation)

2.1.1 TERMS

The semiotic square is composed of four terms:

Position 1 (term A)
Position 2 (term B)
Position 3 (term not-B)
Position 4 (term not-A)

The first two terms form the opposition (the contrary relationship) that is the basis of the square, and the other two are obtained by negating each term of the opposition.

2.1.2 METATERMS

The semiotic square includes six metaterms. The metaterms are terms created from the four simple terms. Some of the metaterms have been named. (The complex term and the neutral term, despite their names, are indeed metaterms).

Position 5 (term 1 + term 2): complex term
Position 6 (term 3 + term 4): neutral term
Position 7 (term 1 + term 3): positive deixis
Position 8 (term 2 + term 4): negative deixis
Position 9 = term 1 + term 4: unnamed
Position 10 = term 2 + term 3: unnamed

These ten “positions” are apparently meant to explain Jameson’s remark.

Hébert’s treatment has considerably greater entertainment value than Osborn’s. Besides “the living dead” and angels, Hébert’s examples and exercises include vampires, transvestites, the Passion of Christ, and the following very relevant quotation:

“Simply let your ‘Yes’ be ‘Yes,’ and your ‘No,’ ‘No’; anything beyond this comes from the evil one.” (Matthew 5:37)

Wednesday, March 4, 2009

Wednesday March 4, 2009

Filed under: General — m759 @ 10:07 pm
Cover Art

Cover of 'Angels & Demons,' paperback ISBN-10 0671027360

As religious fictions go,
I prefer…

De Angelis

“Richardson leaned forward and picked up from the table a very old bound book and a very fat exercise book. He again settled himself in his chair, and said, looking firmly at Anthony– ‘This is the De Angelis of Marcellus Victorinus of Bologna, published in the year 1514 at Paris, and dedicated to Leo X.’

‘Is it?’ Anthony said uncertainly.”

— Charles Williams, The Place of the Lion, 1931

Cover by Jim Lamb for 'The Place of the Lion,' Eerdmans 1979 paperback, ISBN-10 0802812228

For more about the artist,
see an entry at the weblog
“Through the Wardrobe”
on Aug. 18, 2008.

Related material:
 previous entry.

Monday, December 1, 2008

Monday December 1, 2008

Filed under: General — Tags: — m759 @ 12:00 pm
Pictures at
an Exhibition

Day Without Art:

Day Without Art logo: X'd-out frame

and therefore…

Art:

Art logo: frame not X'd out

From Braque's birthday, 2006:

"The senses deform, the mind forms. Work to perfect the mind. There is no certitude but in what the mind conceives."

— Georges Braque,
   Reflections on Painting, 1917

Those who wish to follow Braque's advice may try the following exercise from a book first published in 1937:

Carmichael on groups, exercise, p. 440
Hint: See the following
construction of a tesseract:
 
Point, line, square, cube, tesseract
From a page by Bryan Clair

For a different view
of the square and cube
see yesterday's entry
Abstraction and Faith.

Sunday, November 23, 2008

Sunday November 23, 2008

Filed under: General,Geometry — m759 @ 9:00 am
The Idea of Identity

“The first credential
 we should demand of a critic
 is his ideograph of the good.”

— Ezra Pound,
  How to Read

Music critic Bernard Holland in The New York Times on Monday, May 20, 1996:

The Juilliard’s
Half-Century Ripening

Philosophers ponder the idea of identity: what it is to give something a name on Monday and have it respond to that name on Friday regardless of what might have changed in the interim. Medical science tells us that the body’s cells replace themselves wholesale within every seven years, yet we tell ourselves that we are what we were….

Schubert at the end of his life had already passed on to another level of spirit. Beethoven went back and forth between the temporal world and the world beyond right up to his dying day.

Exercise

Part I:
Apply Holland’s Monday-to-Friday “idea of identity” to the lives and deaths during the week of Monday, Nov. 10 (“Frame Tales“), through Friday, Nov. 14, of a musician and a maker of music documentaries– Mitch Mitchell (d. Nov. 12) and Baird Bryant (d. Nov. 13).

Part II:
Apply Holland’s “idea of identity” to last week (Monday, Nov. 17, through Friday, Nov. 21), combining it with Wigner’s remarks on invariance (discussed here on Monday) and with the “red dragon” (Log24, Nov. 15) concept of flight over “the Hump”– the Himalayas– and the 1991 documentary filmed by Bryant, “Heart of Tibet.”

Part III:

Discuss Parts I and II in the context of Eliot’s Four Quartets. (See Time Fold, The Field of Reason, and Balance.)

Friday, August 22, 2008

Friday August 22, 2008

Filed under: General,Geometry — Tags: , — m759 @ 5:01 am

Tentative movie title:
Blockheads

Kohs Block Design Test

The Kohs Block Design
Intelligence Test

Samuel Calmin Kohs, the designer (but not the originator) of the above intelligence test, would likely disapprove of the "Aryan Youth types" mentioned in passing by a film reviewer in today's New York Times. (See below.) The Aryan Youth would also likely disapprove of Dr. Kohs.

Related material from
Notes on Finite Geometry:

Kohs Block Design figure illustrating the four-color decomposition theorem

Other related material:

1.  Wechsler Cubes (intelligence testing cubes derived from the Kohs cubes shown above). See…

Harvard psychiatry and…
The Montessori Method;
The Crimson Passion;
The Lottery Covenant.

2.  Wechsler Cubes of a different sort (Log24, May 25, 2008)

3.  Manohla Dargis in today's New York Times:

"… 'Momma’s Man' is a touchingly true film, part weepie, part comedy, about the agonies of navigating that slippery slope called adulthood. It was written and directed by Azazel Jacobs, a native New Yorker who has set his modestly scaled movie with a heart the size of the Ritz in the same downtown warren where he was raised. Being a child of the avant-garde as well as an A student, he cast his parents, the filmmaker Ken Jacobs and the artist Flo Jacobs, as the puzzled progenitors of his centerpiece, a wayward son of bohemia….

In American movies, growing up tends to be a job for either Aryan Youth types or the oddballs and outsiders…."

4.  The bohemian who named his son Azazel:

"… I think that the deeper opportunity, the greater opportunity film can offer us is as an exercise of the mind. But an exercise, I hate to use the word, I won't say 'soul,' I won't say 'soul' and I won't say 'spirit,' but that it can really put our deepest psychological existence through stuff. It can be a powerful exercise. It can make us think, but I don't mean think about this and think about that. The very, very process of powerful thinking, in a way that it can afford, is I think very, very valuable. I basically think that the mind is not complete yet, that we are working on creating the mind. Okay. And that the higher function of art for me is its contribution to the making of mind."

Interview with Ken Jacobs, UC Berkeley, October 1999

5.  For Dargis's "Aryan Youth types"–

From a Manohla Dargis
New York Times film review
of April 4, 2007
   (Spy Wednesday) —

Scene from Paul Verhoeven's film 'Black Book'

See also, from August 1, 2008
(anniversary of Hitler's
opening the 1936 Olympics) —

For Sarah Silverman

and the 9/9/03 entry 

Olympic Style.

Doonesbury,
August 21-22, 2008:

http://www.log24.com/log/pix08A/080821-22-db16color.gif
 

Friday, July 25, 2008

Friday July 25, 2008

56 Triangles

Greg Egan's drawing of the 56 triangles on the Klein quartic 3-hole torus

John Baez on
Klein's quartic:

"This wonderful picture was drawn by Greg Egan with the help of ideas from Mike Stay and Gerard Westendorp. It's probably the best way for a nonmathematician to appreciate the symmetry of Klein's quartic. It's a 3-holed torus, but drawn in a way that emphasizes the tetrahedral symmetry lurking in this surface! You can see there are 56 triangles: 2 for each of the tetrahedron's 4 corners, and 8 for each of its 6 edges."

Exercise:

The Eightfold Cube: The Beauty of Klein's Simple Group

Click on image for further details.

Note that if eight points are arranged
in a cube (like the centers of the
eight subcubes in the figure above),
there are 56 triangles formed by
the 8 points taken 3 at a time.

Baez's discussion says that the Klein quartic's 56 triangles can be partitioned into 7 eight-triangle Egan "cubes" that correspond to the 7 points of the Fano plane in such a way that automorphisms of the Klein quartic correspond to automorphisms of the Fano plane. Show that the 56 triangles within the eightfold cube can also be partitioned into 7 eight-triangle sets that correspond to the 7 points of the Fano plane in such a way that (affine) transformations of the eightfold cube induce (projective) automorphisms of the Fano plane.

Sunday, May 25, 2008

Sunday May 25, 2008

Filed under: General,Geometry — Tags: — m759 @ 6:30 pm
Hall of Mirrors

Epigraph to
Deploying the Glass Bead Game, Part II,”
by Robert de Marrais:

“For a complete logical argument,”
Arthur began
with admirable solemnity,
“we need two prim Misses –”
“Of course!” she interrupted.
“I remember that word now.
And they produce — ?”
“A Delusion,” said Arthur.

— Lewis Carroll,
Sylvie and Bruno

Prim Miss 1:

Erin O’Connor’s weblog
“Critical Mass” on May 24:

Roger Rosenblatt’s Beet [Ecco hardcover, Jan. 29, 2008] is the latest addition to the noble sub-genre of campus fiction….

Curricular questions and the behavior of committees are at once dry as dust subjects and areas ripe for sarcastic send-up– not least because, as dull as they are, they are really both quite vital to the credibility and viability of higher education.

Here’s an excerpt from the first meeting, in which committee members propose their personal plans for a new, improved curriculum:

“… Once the students really got into playing with toy soldiers, they would understand history with hands-on excitement.”

To demonstrate his idea, he’d brought along a shoe box full of toy doughboys and grenadiers, and was about to reenact the Battle of Verdun on the committee table when Heilbrun stayed his hand. “We get it,” he said.

“That’s quite interesting, Molton,” said Booth [a chemist]. “But is it rigorous enough?”

At the mention of the word, everyone, save Peace, sat up straight.

“Rigor is so important,” said Kettlegorf.

“We must have rigor,” said Booth.

“You may be sure,” said the offended Kramer. “I never would propose anything lacking rigor.”

Smythe inhaled and looked at the ceiling. “I think I may have something of interest,” he said, as if he were at a poker game and was about to disclose a royal flush. “My proposal is called ‘Icons of Taste.’ It would consist of a galaxy of courses affixed to several departments consisting of lectures on examples of music, art, architecture, literature, and other cultural areas a student needed to indicate that he or she was sophisticated.”

“Why would a student want to do that?” asked Booth.

“Perhaps sophistication is not a problem for chemists,” said Smythe. Lipman tittered.

“What’s the subject matter?” asked Heilbrun. “Would it have rigor?”

“Of course it would have rigor. Yet it would also attract those additional students Bollovate is talking about.” Smythe inhaled again. “The material would be carefully selected,” he said. “One would need to pick out cultural icons the students were likely to bring up in conversation for the rest of their lives, so that when they spoke, others would recognize their taste as being exquisite yet eclectic and unpredictable.”

“You mean Rembrandt?” said Kramer.

Smythe smiled with weary contempt. “No, I do not mean Rembrandt. I don’t mean Beethoven or Shakespeare, either, unless something iconic has emerged about them to justify their more general appeal.”

“You mean, if they appeared on posters,” said Lipman.

“That’s it, precisely.”

Lipman blushed with pride.

“The subject matter would be fairly easy to amass,” Smythe said. “We could all make up a list off the top of our heads. Einstein–who does have a poster.” He nodded to the ecstatic Lipman. “Auden, for the same reason. Students would need to be able to quote ‘September 1939[ or at least the last lines. And it would be good to teach ‘Musee des Beaux Arts’ as well, which is off the beaten path, but not garishly. Mahler certainly. But Cole Porter too. And Sondheim, I think. Goya. Warhol, it goes without saying, Stephen Hawking, Kurosawa, Bergman, Bette Davis. They’d have to come up with some lines from Dark Victory, or better still, Jezebel. La Dolce Vita. Casablanca. King of Hearts. And Orson, naturally. Citizen Kane, I suppose, though personally I prefer F for Fake.”

“Judy!” cried Heilbrun.

“Yes, Judy too. But not ‘Over the Rainbow.’ It would be more impressive for them to do ‘The Trolley Song,’ don’t you think?” Kettlegorf hummed the intro.

Guernica,” said Kramer. “Robert Capa.” Eight-limbed asterisk

“Edward R. Murrow,” said Lipman.

“No! Don’t be ridiculous!” said Smythe, ending Lipman’s brief foray into the world of respectable thought.

“Marilyn Monroe!” said Kettlegorf.

“Absolutely!” said Smythe, clapping to indicate his approval.

“And the Brooklyn Bridge,” said Booth, catching on. “And the Chrysler Building.”

“Maybe,” said Smythe. “But I wonder if the Chrysler Building isn’t becoming something of a cliche.”

Peace had had enough. “And you want students to nail this stuff so they’ll do well at cocktail parties?”

Smythe sniffed criticism, always a tetchy moment for him. “You make it sound so superficial,” he said.

Prim Miss 2:

Siri Hustvedt speaks at Adelaide Writers’ Week– a story dated March 24, 2008

“I have come to think of my books as echo chambers or halls of mirrors in which themes, ideas, associations continually reflect and reverberate inside a text. There is always point and counterpoint, to use a musical illustration. There is always repetition with difference.”

A Delusion:

Exercise — Identify in the following article the sentence that one might (by unfairly taking it out of context) argue is a delusion.

(Hint: See Reflection Groups in Finite Geometry.)

A. V. Borovik, 'Maroids and Coxeter Groups'

Why Borovik’s Figure 4
is included above:

Euclid, Peirce, L’Engle:
No Royal Roads.

For more on Prim Miss 2
and deploying
the Glass Bead Game,
see the previous entry.

The image “http://www.log24.com/log/images/asterisk8.gif” cannot be displayed, because it contains errors. And now, perhaps, his brother Cornell Capa, who died Friday.

 Related material: Log24 on March 24– Death and the Apple Tree— with an excerpt from
George MacDonald, and an essay by David L. Neuhouser mentioning the influence of MacDonald on Lewis Carroll– Lewis Carroll: Author, Mathematician, and Christian (pdf).

Thursday, May 22, 2008

Thursday May 22, 2008

Filed under: General,Geometry — Tags: , — m759 @ 9:00 am
The Undertaking:
An Exercise in
Conceptual Art

I Ching hexagram 54: The Marrying Maiden

Hexagram 54:
THE JUDGMENT

Undertakings bring misfortune.
Nothing that would further.

The image “http://www.log24.com/log/pix08/080522-Irelandslide1.jpg” cannot be displayed, because it contains errors.

Brian O’Doherty, an Irish-born artist,
before the [Tuesday, May 20] wake
of his alter ego* ‘Patrick Ireland’
on the grounds of the
Irish Museum of Modern Art.”
New York Times, May 22, 2008    

THE IMAGE

Thus the superior man
understands the transitory
in the light of
the eternity of the end.

Another version of
the image:

Images of time and eternity in memory of Michelangelo
See 2/22/08
and  4/19/08.


Related material:

Michael Kimmelman in today’s New York Times

“An essay from the ’70s by Mr. O’Doherty, ‘Inside the White Cube,’ became famous in art circles for describing how modern art interacted with the gallery spaces in which it was shown.”

Brian O’Doherty, “Inside the White Cube,” 1976 Artforum essays on the gallery space and 20th-century art:

“The history of modernism is intimately framed by that space. Or rather the history of modern art can be correlated with changes in that space and in the way we see it. We have now reached a point where we see not the art but the space first…. An image comes to mind of a white, ideal space that, more than any single picture, may be the archetypal image of 20th-century art.”

An archetypal image

THE SPACE:

The Eightfold Cube: The Beauty of Klein's Simple Group

A non-archetypal image

THE ART:

Jack in the Box, by Natasha Wescoat

Natasha Wescoat, 2004
See also Epiphany 2008:

How the eightfold cube works

“Nothing that would further.”
— Hexagram 54

Lear’s fool:

 …. Now thou art an 0
without a figure. I am better
than thou art, now. I am a fool;
thou art nothing….

“…. in the last mystery of all the single figure of what is called the World goes joyously dancing in a state beyond moon and sun, and the number of the Trumps is done.  Save only for that which has no number and is called the Fool, because mankind finds it folly till it is known.  It is sovereign or it is nothing, and if it is nothing then man was born dead.”

The Greater Trumps,
by Charles Williams, Ch. 14

* For a different, Jungian, alter ego, see Irish Fourplay (Jan. 31, 2003) and “Outside the Box,” a New York Times review of O’Doherty’s art (featuring a St. Bridget’s Cross) by Bridget L. Goodbody dated April 25, 2007. See also Log24 on that date.

Saturday, April 19, 2008

Saturday April 19, 2008

Filed under: General,Geometry — Tags: , — m759 @ 5:01 am
A Midrash for Benedict

On April 16, the Pope’s birthday, the evening lottery number in Pennsylvania was 441. The Log24 entries of April 17 and April 18 supplied commentaries based on 441’s incarnation as a page number in an edition of Heidegger’s writings.  Here is a related commentary on a different incarnation of 441.  (For a context that includes both today’s commentary and those of April 17 and 18, see Gian-Carlo Rota– a Heidegger scholar as well as a mathematician– on mathematical Lichtung.)

From R. D. Carmichael, Introduction to the Theory of Groups of Finite Order (Boston, Ginn and Co., 1937)– an exercise from the final page, 441, of the final chapter, “Tactical Configurations”–

“23. Let G be a multiply transitive group of degree n whose degree of transitivity is k; and let G have the property that a set S of m elements exists in G such that when k of the elements S are changed by a permutation of G into k of these elements, then all these m elements are permuted among themselves; moreover, let G have the property P, namely, that the identity is the only element in G which leaves fixed the nm elements not in S.  Then show that G permutes the m elements S into

n(n -1) … (nk + 1)
____________________

m(m – 1) … (mk + 1)

sets of m elements each, these sets forming a configuration having the property that any (whatever) set of k elements appears in one and just one of these sets of m elements each. Discuss necessary conditions on m, n, k in order that the foregoing conditions may be realized. Exhibit groups illustrating the theorem.”

This exercise concerns an important mathematical structure said to have been discovered independently by the American Carmichael and by the German Ernst Witt.

For some perhaps more comprehensible material from the preceding page in Carmichael– 440– see Diamond Theory in 1937.

Saturday, February 23, 2008

Saturday February 23, 2008

Filed under: General,Geometry — Tags: , , , — m759 @ 12:00 pm
Jumpers

"An acute study of the links
between word and fact"
Nina daVinci Nichols

 
Thanks to a Virginia reader for a reminder:
 
Virginia /391062427/item.html? 2/22/2008 7:37 PM
 
The link is to a Log24 entry
that begins as follows…

An Exercise

of Power

Johnny Cash:
"And behold,
a white horse."

Springer logo - A chess knight
Chess Knight
(in German, Springer)

This, along with the "jumper" theme in the previous two entries, suggests a search on springer jumper.That search yields a German sports phrase, "Springer kommt!"  A search on that phrase yields the following:
"Liebe Frau vBayern,
mich würde interessieren wie man
mit diesem Hintergrund
(vonbayern.de/german/anna.html)
zu Springer kommt?"

Background of "Frau vBayern" from thePeerage.com:

Anna-Natascha Prinzessin zu Sayn-Wittgenstein-Berleburg 

F, #64640, b. 15 March 1978Last Edited=20 Oct 2005

     Anna-Natascha Prinzessin zu Sayn-Wittgenstein-Berleburg was born on 15 March 1978. She is the daughter of Ludwig Ferdinand Prinz zu Sayn-Wittgenstein-Berleburg and Countess Yvonne Wachtmeister af Johannishus. She married Manuel Maria Alexander Leopold Jerg Prinz von Bayern, son of Leopold Prinz von Bayern and Ursula Mohlenkamp, on 6 August 2005 at Nykøping, Södermanland, Sweden.

The date of the above "Liebe Frau vBayern" inquiry, Feb. 1, 2007, suggests the following:

From Log24 on
St. Bridget's Day, 2007:

The quotation
"Science is a Faustian bargain"
and the following figure–

Change

The 63 yang-containing hexagrams of the I Ching as a Singer 63-cycle

From a short story by
the above Princess:

"'I don't even think she would have wanted to change you. But she for sure did not want to change herself. And her values were simply a part of her.' It was true, too. I would even go so far as to say that they were her basis, if you think about her as a geometrical body. That's what they couldn't understand, because in this age of the full understanding for stretches of values in favor of self-realization of any kind, it was a completely foreign concept."

To make this excellent metaphor mathematically correct,
change "geometrical body" to "space"… as in

"For Princeton's Class of 2007"

Review of a 2004 production of a 1972 Tom Stoppard play, "Jumpers"–

John Lahr on Tom Stoppard's play Jumpers

Related material:

Knight Moves (Log24, Jan. 16),
Kindergarten Theology (St. Bridget's Day, 2008),
and

The image “My space -(the affine space of six dimensions over the two-element field
(Click on image for details.)

Tuesday, July 17, 2007

Tuesday July 17, 2007

Filed under: General — Tags: — m759 @ 7:00 am
Habeas Corpus
 
The Hex Witch of Seldom,
by Nancy Springer:

Hex Witch of Seldom - Excerpt on squares of breadT

Log24 on 9/11, 2003
:

Here is a rhetorical exercise
for Jesuits that James Joyce
might appreciate:

Discuss Bobbi’s “little squares”
of bread as the Body of Christ.
Formulate, using Santayana’s
criteria, a definition of beauty
that includes this sacrament.

Thursday, May 10, 2007

Thursday May 10, 2007

Filed under: General — m759 @ 10:00 pm
Riverdance

The image “http://www.log24.com/log/pix07/070510-Dance.jpg” cannot be displayed, because it contains errors.

The above scene from
The Best of Riverdance
furnishes an exercise in
what Victor Turner has called
comparative symbology.”

The circular symbol at top
may be seen as representing
the solar deity Apollo,
Leader of the Muses.

The nine female dancers
may be seen as
the nine muses,
with Jean Butler
at the center
as Terpsichore,
Muse of Dance.

Related Material —

ART WARS:
To Apollo

The image “http://www.log24.com/theory/images/grid3x3.gif” cannot be displayed, because it contains errors.

“This is the garden of Apollo,
the field of Reason….”
John Outram, architect

For another look at
Terpsichore in action,
see Jean Butler at
CRC Irish Dance Camp.

For those who prefer
a different sort of camp
there is of course
Xanadu.

I prefer Butler.

Sunday, March 18, 2007

Sunday March 18, 2007

Filed under: General,Geometry — m759 @ 2:20 pm

Update to
The Geometry of Logic:

A detailed description of a group of 16 “logical automorphisms” of the 16 binary connectives has been given in the paper “Simetria y Logica: La notacion de Peirce para los 16 conectivos binarios,” by Mireya Garcia, Jhon Fredy Gomez, and Arnold Oostra. (Published in the Memorias del XII Encuentro de Geometria y sus Aplicaciones, Universidad Pedagogica Nacional, Bogota, June 2001; on the Web at http://www.unav.es/gep/Articulos/SimetriaYLogica.pdf.) The authors do not identify this group as a subgroup of the affine group of A (the finite affine geometry of four dimensions over the two-element field); this can serve as an exercise.  Another exercise: determining whether the authors’ order-16 group includes all transformations that might reasonably be called “logical automorphisms” of the 16 binary connectives.

Sunday, February 25, 2007

Sunday February 25, 2007

Filed under: General — Tags: — m759 @ 10:31 am

Between Two Worlds

Nicolas Cage as Ghost Rider

Nicolas Cage as Ghost Rider

"I'm the only one who can
walk in both worlds.
I'm T. S. Eliot."
 
Four Quartets:

I caught the sudden look of some dead master
Whom I had known, forgotten, half recalled
     Both one and many; in the brown baked features
     The eyes of a familiar compound ghost
Both intimate and unidentifiable.
     So I assumed a double part, and cried
     And heard another's voice cry: 'What! are you here?'
Although we were not. I was still the same,
     Knowing myself yet being someone other—
     And he a face still forming; yet the words sufficed
To compel the recognition they preceded.
     And so, compliant to the common wind,
     Too strange to each other for misunderstanding,
In concord at this intersection time
     Of meeting nowhere, no before and after,
     We trod the pavement in a dead patrol.
I said: 'The wonder that I feel is easy,
     Yet ease is cause of wonder. Therefore speak:
     I may not comprehend, may not remember.'
And he: 'I am not eager to rehearse
     My thoughts and theory which you have forgotten.
     These things have served their purpose: let them be.
So with your own, and pray they be forgiven
     By others, as I pray you to forgive
     Both bad and good. Last season's fruit is eaten
And the fullfed beast shall kick the empty pail.
     For last year's words belong to last year's language
     And next year's words await another voice.
But, as the passage now presents no hindrance
     To the spirit unappeased and peregrine
     Between two worlds become much like each other,
So I find words I never thought to speak
     In streets I never thought I should revisit
     When I left my body on a distant shore.
Since our concern was speech, and speech impelled us
     To purify the dialect of the tribe
     And urge the mind to aftersight and foresight,
Let me disclose the gifts reserved for age
     To set a crown upon your lifetime's effort.
     First, the cold friction of expiring sense
Without enchantment, offering no promise
     But bitter tastelessness of shadow fruit
     As body and soul begin to fall asunder.
Second, the conscious impotence of rage
     At human folly, and the laceration
     Of laughter at what ceases to amuse.
And last, the rending pain of re-enactment
     Of all that you have done, and been; the shame
     Of motives late revealed, and the awareness
Of things ill done and done to others' harm
     Which once you took for exercise of virtue.
     Then fools' approval stings, and honour stains.
From wrong to wrong the exasperated spirit
     Proceeds, unless restored by that refining fire
     Where you must move in measure, like a dancer.'

Thursday, February 15, 2007

Thursday February 15, 2007

Filed under: General — m759 @ 6:25 am
Pop!

From “Music and Lyrics” (2007)

Yesterday, Valentine’s Day, Hollywood released a romantic comedy, “Music and Lyrics,” based on a fictional reality-TV show called “Battle of the 80’s Has-Beens.”

This, along with the Feb. 13 Log24 entry touching on both pop science and pop music, and the fact that today is the anniversary of the 1988 death of physicist Richard Feynman, suggests the following exercise:

Compare and contrast the lives and works of Feynman (May 11, 1918 – Feb. 15, 1988) and the late Carl Sagan (Nov. 9, 1934 – Dec. 20, 1996).

(Being dead, both are, in a sense, has-beens, and both were popular in the 1980’s.)

I personally regard Feynman as one of science’s saints, and Sagan as, shall we say, a non-saint.  For some related reflections on pop science and pop music, see the five Log24 entries ending on Michaelmas 2002.  And then there is popcorn–

A 1980’s Hollywood ending
that Feynman may have liked:

The image “http://www.log24.com/log/pix07/070215-Popcorn.jpg” cannot be displayed, because it contains errors.

Click on picture for details.

 “… slow-motion romp
   through the popcorn…
Tears for Fears’
‘Everybody Wants to
Rule the World’ ramps up
on the soundtrack….”
Credits.

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