Tuesday, July 9, 2024
Sunday, October 8, 2023
Annals of Figurate Space . . .
World Space Week: A Golem for Bloom
From Friday's "Introduction to Multispeech" —
"Students of Multispeech must become familiar with the
Entendre family — Single, Double, Triple, and so forth."
From Finnegans Wake —
Comments Off on Annals of Figurate Space . . .
World Space Week: A Golem for Bloom
World Space Week: A Golem for Bloom
Friday, September 22, 2023
Figurate Space
For the purpose of defining figurate geometry , a figurate space might be
loosely described as any space consisting of finitely many congruent figures —
subsets of Euclidean space such as points, line segments, squares,
triangles, hexagons, cubes, etc., — that are permuted by some finite group
acting upon them.
Thus each of the five Platonic solids constructed at the end of Euclid's Elements
is itself a figurate space, considered as a collection of figures — vertices, edges,
faces — seen in the nineteenth century as acted upon by a group of symmetries .
More recently, the 4×6 array of points (or, equivalently, square cells) in the Miracle
Octad Generator of R. T. Curtis is also a figurate space . The relevant group of
symmetries is the large Mathieu group M24 . That group may be viewed as acting
on various subsets of a 24-set… for instance, the 759 octads that are analogous
to the faces of a Platonic solid. The geometry of the 4×6 array was shown by
Curtis to be very helpful in describing these 759 octads.
Comments Off on Figurate Space
Wednesday, September 20, 2023
Temple Talk
Comments Off on Temple Talk
Tuesday, September 19, 2023
Figurate Geometry
The above title for a new approach to finite geometry
was suggested by the old phrase "figurate numbers."
See other posts in this journal now tagged Figurate Geometry.
Update of 10 AM ET on Sept. 19, 2023 —
Related material from social media:
Update of 10:30 AM ET Sept. 19 —
A related topic from figurate geometry:
Comments Off on Figurate Geometry
Monday, September 18, 2023
The Passage of Time
The figure above summarizes a new way of looking at
so-called "figurate numbers." The old way goes back
at least to the time of Pythagoras.
A more explicit presentation —
Comments Off on The Passage of Time
Sunday, January 22, 2023
The Stillwell Dichotomies
| Number | Space |
| Arithmetic | Geometry |
| Discrete | Continuous |
Related literature —
From a "Finite Fields in 1956" post —
The Nutshell:
Related Narrative:
Comments Off on The Stillwell Dichotomies
Thursday, January 5, 2023
Logic and Geometry at Harvard
Comments Off on Logic and Geometry at Harvard
Monday, October 17, 2022
Sunday, June 26, 2022
Mockery Day
For Monty Python —
"Glastonbury has been described as having a New Age community[6]
and possibly being where New Age beliefs originated at the turn of
the twentieth century.[7] It is notable for myths and legends often
related to Glastonbury Tor, concerning Joseph of Arimathea, the
Holy Grail and King Arthur." — Wikipedia
For American Democracy —
Related mockery from 2012 —
See also "Triangles Are Square" in 1984 —
Comments Off on Mockery Day
Thursday, June 23, 2022
The Nutshell Suite
The above is a summary of
Pythagorean philosophy
reposted here on . . .
Battle of the Nutshells:
From a much larger nutshell
on the above Pythagorean date—
Now let's dig a bit deeper into history . . .
Comments Off on The Nutshell Suite
Wednesday, June 22, 2022
Code Wars: “Use the Source, Luke.”
Click the above galaxy for a larger image.
"O God, I could be bounded in a nutshell
and count myself a king of infinite space,
were it not that I have bad dreams." — Hamlet
Battle of the Nutshells —
From a much larger nutshell
on the above code date—
Comments Off on Code Wars: “Use the Source, Luke.”
Sunday, June 12, 2022
Vocabulary: Trisquare Theorem
See also trisquare.space.
Comments Off on Vocabulary: Trisquare Theorem
Friday, May 20, 2022
Squares to Triangles
Comments Off on Squares to Triangles
Monday, April 25, 2022
Annals of Mathematical History
Some related remarks —
Comments Off on Annals of Mathematical History
Sunday, August 15, 2021
Simple Similarity
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 —
Comments Off on Simple Similarity
Friday, May 15, 2020
Review
Charles Taylor,
“Epiphanies of Modernism,”
Chapter 24 of Sources of the Self
(Cambridge U. Press, 1989, p. 477) —
“… the object sets up
a kind of frame or space or field
within which there can be epiphany.”
See also Talking of Michelangelo.
Related material for comedians —
Literature ad absurdum —
Comments Off on Review
Thursday, February 13, 2020
Square-Triangle Mappings: The Continuous Case
On Feb. 11, Christian Lawson-Perfect posed an interesting question
about mappings between square and triangular grids:
For the same question posed about non -continuous bijections,
see "Triangles are Square."
I posed the related non– continuous question in correspondence in
the 1980's, and later online in 2012. Naturally, I wondered in the
1980's about the continuous question and conformal mappings,
but didn't follow up that line of thought.
Perfect last appeared in this journal on May 20, 2014,
in the HTML title line for the link "offensive."
Comments Off on Square-Triangle Mappings: The Continuous Case
Wednesday, November 27, 2019
A Companion-Piece for the Circular Rectangle:
For the circular rectangle, see today's earlier post "Enter Jonathan Miller…."
A recent view of the above address —
Comments Off on A Companion-Piece for the Circular Rectangle:
Saturday, June 29, 2019
That’s “Merry” … And Quite Contrary
"John Horton Conway is a cross between
Archimedes, Mick Jagger and Salvador Dalí."
— The Guardian paraphrasing Siobhan Roberts,
John Horton Conway and his Leech lattice doodle
in The Guardian . Photo: Hollandse Hoogte/Eyevine.
. . . .
"In junior school, one of Conway’s teachers had nicknamed him 'Mary'.
He was a delicate, effeminate creature. Being Mary made his life
absolute hell until he moved on to secondary school, at Liverpool’s
Holt High School for Boys. Soon after term began, the headmaster
called each boy into his office and asked what he planned to do with
his life. John said he wanted to read mathematics at Cambridge.
Instead of 'Mary' he became known as 'The Prof'. These nicknames
confirmed Conway as a terribly introverted adolescent, painfully aware
of his own suffering." — Siobhan Roberts, loc. cit.
From the previous post —
See as well this journal on the above Guardian date —
Comments Off on That’s “Merry” … And Quite Contrary
Thursday, May 2, 2019
Squaring the Triangle
"Having squared the circle is a famous crank assertion." — Wikipedia
Squaring the circle was proved impossible by Lindemann in 1882.
Squaring the triangle is, however, possible — indeed, trivial —
and is more closely related to the saying quoted by Jung —
"All things do live in the three
But in the four they merry be."
Comments Off on Squaring the Triangle
Thursday, February 28, 2019
Fooling
The two books pictured above are From Discrete to Continuous ,
by Katherine Neal, and Geometrical Landscapes , by Amir Alexander.
Note: There is no Galois (i.e., finite) field with six elements, but
the theory of finite fields underlies applications of six-set geometry.
Comments Off on Fooling
Saturday, June 23, 2018
Meanwhile …
Backstory for fiction fans, from Log24 on June 11 —
Related non -fiction —
See as well the structure discussed in today's previous post.
Comments Off on Meanwhile …
Monday, June 11, 2018
Arty Fact
The title was suggested by the name "ARTI" of an artificial
intelligence in the new film 2036: Origin Unknown.
The Eye of ARTI —
See also a post of May 19, "Uh-Oh" —
— and a post of June 6, "Geometry for Goyim" —
Mystery box merchandise from the 2011 J. J. Abrams film Super 8
An arty fact I prefer, suggested by the triangular computer-eye forms above —
This is from the July 29, 2012, post The Galois Tesseract.
See as well . . .
Comments Off on Arty Fact
Tuesday, April 17, 2018
A Necessary Possibility*
"Without the possibility that an origin can be lost, forgotten, or
alienated into what springs forth from it, an origin could not be
an origin. The possibility of inscription is thus a necessary possibility,
one that must always be possible."
— Rodolphe Gasché, The Tain of the Mirror ,
Harvard University Press, 1986
An inscription from 2010 —
An inscription from 1984 —
|
American Mathematical Monthly, June-July 1984, p. 382 MISCELLANEA, 129 Triangles are square
"Every triangle consists of n congruent copies of itself" |
* See also other Log24 posts mentioning this phrase.
Comments Off on A Necessary Possibility*
Monday, December 25, 2017
Every Picture Tells a Story
The movie marquee below
("Batman" and "Lethal Weapon 2")
indicates that the recent film "IT"
is set in the summer of 1989.
The marquee suggests a review. Also . . . .
"… the thing that has shown up every twenty-seven years
or so . . . . It always comes back, you see. It."
— King, Stephen. IT (p. 151). Scribner. Kindle Edition.
Note that the flashback summer in King's book,
1958… plus 27 is 1985… plus 27 is 2012.
Comments Off on Every Picture Tells a Story
Wednesday, October 4, 2017
Text and Context
Text —
"A field is perhaps the simplest algebraic structure we can invent."
— Hermann Weyl, 1952
Context —
See also yesterday's Personalized Book Search.
|
Full text of Symmetry – Internet Archive — https://archive.org/details/Symmetry_482
A field is perhaps the simplest algebraic 143 structure |
From a Log24 search for Mathematics+Nutshell —
Comments Off on Text and Context
Monday, October 2, 2017
The Nut Analogy
Published as the final chapter, Chapter 13, in
Episodes in the History of Modern Algebra (1800-1950) ,
edited by Jeremy J. Gray and Karen Hunger Parshall,
American Mathematical Society, July 18, 2007, pages 301-326.
See also this journal on the above McLarty date —
May 24, 2003: Mental Health Month, Day 24.
Comments Off on The Nut Analogy
Wednesday, September 13, 2017
Summer of 1984
The previous two posts dealt, rather indirectly, with
the notion of "cube bricks" (Cullinane, 1984) —
Group actions on partitions —
Cube Bricks 1984 —
Another mathematical remark from 1984 —
For further details, see Triangles Are Square.
Comments Off on Summer of 1984
Sunday, April 16, 2017
Art Space Paradigm Shift
This post’s title is from the tags of the previous post —
The title’s “shift” is in the combined concepts of …
Space and Number
From Finite Jest (May 27, 2012):
The books pictured above are From Discrete to Continuous ,
by Katherine Neal, and Geometrical Landscapes , by Amir Alexander.
For some details of the shift, see a Log24 search for Boole vs. Galois.
From a post found in that search —
“Benedict Cumberbatch Says
a Journey From Fact to Faith
Is at the Heart of Doctor Strange“
— io9 , July 29, 2016
” ‘This man comes from a binary universe
where it’s all about logic,’ the actor told us
at San Diego Comic-Con . . . .
‘And there’s a lot of humor in the collision
between Easter [ sic ] mysticism and
Western scientific, sort of logical binary.’ “
[Typo now corrected, except in a comment.]
Comments Off on Art Space Paradigm Shift
Sunday, February 12, 2017
Religious Art for Sunday
Euclidean square and triangle—
For some backstory, see the "preface" of the
previous post and Soifer in this journal.
Comments Off on Religious Art for Sunday
Tuesday, December 15, 2015
Square Triangles
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?
Comments Off on Square Triangles
Saturday, November 21, 2015
Brightness at Noon*
A recent not-too-bright book from Princeton —
Some older, brighter books from Tony Zee —
Fearful Symmetry (1986) and
Quantum Field Theory in a Nutshell (2003).
* Continued.
Comments Off on Brightness at Noon*
Sunday, November 1, 2015
Sermon for All Saints’ Day
Comments Off on Sermon for All Saints’ Day
Friday, August 14, 2015
Being Interpreted
The ABC of things —
The ABC of words —
A nutshell —
Book lessons —
Comments Off on Being Interpreted
Tuesday, March 17, 2015
Monday, July 7, 2014
Tricky Task
Roger Cooke in the Notices of the American
Mathematical Society , April 2010 —
"Life on the Mathematical Frontier:
Legendary Figures and Their Adventures"
"In most cases involving the modern era, there
are enough documents to produce a clear picture
of mathematical developments, and conjectures
for which there is no eyewitness or documentary
evidence are not needed. Even so, legends do
arise. (Who has not heard the 'explanation' of
the absence of a Nobel Prize in mathematics?)
The situation is different regarding ancient math-
ematics, however, especially in the period before
Plato’s students began to study geometry. Much
of the prehistory involves allegations about the
mysterious Pythagoreans, and sorting out what is
reliable from what is not is a tricky task.
In this article, I will begin with some modern
anecdotes that have become either legend or
folklore, then work backward in time to take a
more detailed look at Greek mathematics, especially
the Pythagoreans, Plato, and Euclid. I hope at the
very least that the reader finds my examples
amusing, that being one of my goals. If readers
also take away some new insight or mathematical
aphorisms, expressing a sense of the worthiness of
our calling, that would be even better."
Aphorism: "Triangles are square."
(American Mathematical Monthly , June-July 1984)
Insight: The Square-Triangle Theorem.
Comments Off on Tricky Task
Friday, February 21, 2014
Raumproblem*
Despite the blocking of Doodles on my Google Search
screen, some messages get through.
Today, for instance —
"Your idea just might change the world.
Enter Google Science Fair 2014"
Clicking the link yields a page with the following image—
Clearly there is a problem here analogous to
the square-triangle coordinatization problem,
but with the 4×6 rectangle of the R. T. Curtis
Miracle Octad Generator playing the role of
the square.
I once studied this 24-triangle-hexagon
coordinatization problem, but was unable to
obtain any results of interest. Perhaps
someone else will have better luck.
* For a rather different use of this word,
see Hermann Weyl in the Stanford
Encyclopedia of Philosophy.
Comments Off on Raumproblem*
Saturday, January 18, 2014
The Triangle Relativity Problem
A sequel to last night's post The 4×4 Relativity Problem —
In other words, how should the triangle corresponding to
the above square be coordinatized ?
See also a post of July 8, 2012 — "Not Quite Obvious."
Context — "Triangles Are Square," a webpage stemming
from an American Mathematical Monthly item published
in 1984.
Comments Off on The Triangle Relativity Problem
Wednesday, January 8, 2014
Not Subversive, Not Fantasy
The title refers to that of today's previous post, which linked to
a song from the June 1, 1983, album Synchronicity .
(Cf. that term in this journal.)
For some work of my own from the following year, 1984, see…
… as well as the Orwellian dictum Triangles Are Square.
(The cubical figure at left above is from the same month,
if not the same day, as Synchronicity — June 21, 1983.)
Comments Off on Not Subversive, Not Fantasy
Monday, November 25, 2013
Figurate Numbers
The title refers to a post from July 2012:
The above post, a new description of a class of figurate
numbers that has been studied at least since Pythagoras,
shows that the "triangular numbers" of tradition are not
the only triangular numbers.
"Thus the theory of description matters most.
It is the theory of the word for those
For whom the word is the making of the world…."
— Wallace Stevens, "Description Without Place"
See also Finite Relativity (St. Cecilia's Day, 2012).
Comments Off on Figurate Numbers
Sunday, November 24, 2013
Logic for Jews*
The search for 1984 at the end of last evening’s post
suggests the following Sunday meditation.
My own contribution to this genre—
A triangle-decomposition result from 1984:
| American Mathematical Monthly , June-July 1984, p. 382
MISCELLANEA, 129 Triangles are square “Every triangle consists of n congruent copies of itself” |
The Orwell slogans are false. My own is not.
* The “for Jews” of the title applies to some readers of Edward Frenkel.
Comments Off on Logic for Jews*
Monday, November 11, 2013
The Mystic Hexastigm…
Or: The Nutshell
What about Pascal?
For some background on Pascal's mathematics,
not his wager, see…
Richmond, H. W.,
"On the Figure of Six Points in Space of Four Dimensions,"
Quarterly Journal of Pure and Applied Mathematics ,
Volume 31 (1900), pp. 125-160,
dated by Richmond March 30,1899
Richmond, H. W.,
"The Figure Formed from Six Points in Space of Four Dimensions,"
Mathematische Annalen ,
Volume 53 (1900), Issue 1-2, pp 161-176,
dated by Richmond February 1, 1899
See also Nocciolo in this journal.
Recall as well that six points in space may,
if constrained to lie on a circle, be given
a religious interpretation. Richmond's
six points are secular and more general.
Comments Off on The Mystic Hexastigm…
Friday, January 18, 2013
Solomon’s Rep-tiles
"Rep-tiles Revisited," by Viorel Nitica, in MASS Selecta: Teaching and Learning Advanced Undergraduate Mathematics , American Mathematical Society,
"The goal of this note is to take a new look at some of the most amazing objects discovered in recreational mathematics. These objects, having the curious property of making larger copies of themselves, were introduced in 1962 by Solomon W. Golomb [2], and soon afterwards were popularized by Martin Gardner [3] in Scientific American…."
2. S. W. Golomb: "Replicating Figures in the Plane," Mathematical Gazette 48, 1964, 403-412
3. M. Gardner: "On 'Rep-tiles,' Polygons That Can Make Larger and Smaller Copies of Themselves," Scientific American 208, 1963, 154-157
Two such "amazing objects"—
|
Triangle |
Square |
For a different approach to the replicating properties of these objects, see the square-triangle theorem.
For related earlier material citing Golomb, see Not Quite Obvious (July 8, 2012; scroll down to see the update of July 15.).
Golomb's 1964 Gazette article may now be purchased at JSTOR for $14.
Comments Off on Solomon’s Rep-tiles
Wednesday, January 2, 2013
PlanetMath link
Update of May 27, 2013:
The post below is now outdated. See
http://planetmath.org/cullinanediamondtheorem .
__________________________________________________________________
The brief note on the diamond theorem at PlanetMath
disappeared some time ago. Here is a link to its
current URL: http://planetmath.org/?op=getobj;from=lec;id=49.
Update of 3 PM ET Jan. 2, 2013—
Another item recovered from Internet storage:
Click on the Monthly page for some background.
Comments Off on PlanetMath link
Saturday, December 29, 2012
Mapping Problem
A mapping problem posed (informally) in 1985
and solved 27 years later, in 2012:
See also Finite Relativity and Finite Relativity: The Triangular Version.
(A note for fans of the recent film Looper (see previous post)—
Hunter S. Thompson in this journal on February 22, 2005 …
Hunter S. Thompson, photos from The New York Times
… and on March 3, 2009.)
Comments Off on Mapping Problem
Thursday, November 22, 2012
Finite Relativity
(Continued from 1986)
|
S. H. Cullinane This is the relativity problem: to fix objectively a class of equivalent coordinatizations and to ascertain the group of transformations S mediating between them.
— H. Weyl, The Classical Groups , In finite geometry "points" are often defined as ordered n-tuples of a finite (i.e., Galois) field GF(q). What geometric structures ("frames of reference," in Weyl's terms) are coordinatized by such n-tuples? Weyl's use of "objectively" seems to mean that such structures should have certain objective— i.e., purely geometric— properties invariant under each S. This note suggests such a frame of reference for the affine 4-space over GF(2), and a class of 322,560 equivalent coordinatizations of the frame. The frame: A 4×4 array. The invariant structure: The following set of 15 partitions of the frame into two 8-sets.
A representative coordinatization:
0000 0001 0010 0011
The group: The group AGL(4,2) of 322,560 regular affine transformations of the ordered 4-tuples over GF(2). |
S. H. Cullinane This is the relativity problem: to fix objectively a class of equivalent coordinatizations and to ascertain the group of transformations S mediating between them.
— H. Weyl, The Classical Groups , In finite geometry "points" are often defined as ordered n-tuples of a finite (i.e., Galois) field GF(q). What geometric structures ("frames of reference," in Weyl's terms) are coordinatized by such n-tuples? Weyl's use of "objectively" seems to mean that such structures should have certain objective— i.e., purely geometric— properties invariant under each S. This note suggests such a frame of reference for the affine 4-space over GF(2), and a class of 322,560 equivalent coordinatizations of the frame. The frame: An array of 16 congruent equilateral subtriangles that make up a larger equilateral triangle. The invariant structure: The following set of 15 partitions of the frame into two 8-sets.
The group: The group AGL(4,2) of 322,560 regular affine transformations of the ordered 4-tuples over GF(2). |
For some background on the triangular version,
see the Square-Triangle Theorem,
noting particularly the linked-to coordinatization picture.
Comments Off on Finite Relativity
Sunday, July 29, 2012
Defining Form
Background: Square-Triangle Theorem.
For a more literary approach, see "Defining Form" in this journal
and a bibliography from the University of Zaragoza.
Comments Off on Defining Form
Monday, July 16, 2012
Mapping Problem continued
Another approach to the square-to-triangle
mapping problem (see also previous post)—
For the square model referred to in the above picture, see (for instance)
- Picturing the Smallest Projective 3-Space,
- The Relativity Problem in Finite Geometry, and
- Symmetry of Walsh Functions.
Coordinates for the 16 points in the triangular arrays
of the corresponding affine space may be deduced
from the patterns in the projective-hyperplanes array above.
This should solve the inverse problem of mapping,
in a natural way, the triangular array of 16 points
to the square array of 16 points.
Update of 9:35 AM ET July 16, 2012:
Note that the square model's 15 hyperplanes S
and the triangular model's 15 hyperplanes T —
— share the following vector-space structure —
| 0 | c | d | c + d |
| a | a + c | a + d | a + c + d |
| b | b + c | b + d | b + c + d |
| a + b | a + b + c | a + b + d | a + b + c + d |
(This vector-space a b c d diagram is from
Chapter 11 of Sphere Packings, Lattices
and Groups , by John Horton Conway and
N. J. A. Sloane, first published by Springer
in 1988.)
Comments Off on Mapping Problem continued
Sunday, July 15, 2012
Mapping Problem
A trial solution to the
square-to-triangle mapping problem—
Problem: Is there any good definition of "natural"
square-to-triangle mappings according to which
the above mapping is natural (or, for that matter,
un-natural)?
Comments Off on Mapping Problem
Squares Are Triangular
"A figurate number… is a number
that can be represented by
a regular geometrical arrangement
of equally spaced points."
— Eric W. Weisstein at Wolfram MathWorld
For example—
Call a convex polytope P an n-replica if P consists of n
mutually congruent polytopes similar to P packed together.
The square-triangle theorem (or lemma) says that
"Every triangle is an n-replica"
is true if and only if n is a square.
Equivalently,
The positive integer n is a square
if and only if every triangle is an n-replica.
(I.e., squares are triangular.)
This supplies the converse to the saying that
Comments Off on Squares Are Triangular
Saturday, July 14, 2012
Lemma
For example—
A letter to the editor of the American Mathematical Monthly
from the June-July 1985 issue has—
|
… a "square-triangle" lemma:
(∀ t ∈ T , t is an n -replica )
[I.e., "Every triangle is an n -replica" |
For definitions, see the 1985 letter in Triangles Are Square.
(The 1984 lemma discussed there has now, in response to an article
in Wolfram MathWorld, been renamed the square-triangle theorem .)
A search today for related material yielded the following—
|
"Suppose that one side of a triangle has length n . Then it can be cut into n 2 congruent triangles which are similar to the original one and whose corresponding sides to the side of length n have lengths 1." |
This was supplied, without attribution, as part of the official solution
to Problem 3 in the 17th Asian Pacific Mathematics Olympiad
from March 2005. Apparently it seemed obvious to the composer
of the problem. As the 1985 letter notes, it may be not quite obvious.
At any rate, it served in Problem 3 as a lemma , in the sense
described above by Wikipedia. See related remarks by Doron Zeilberger.
Comments Off on Lemma
Tuesday, July 10, 2012
Euclid vs. Galois
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.
Comments Off on Euclid vs. Galois
Sunday, July 8, 2012
Not Quite Obvious
"That n 2 points fall naturally into a triangular array
is a not-quite-obvious fact which may have applications…
and seems worth stating more formally."
— Steven H. Cullinane, letter in the
American Mathematical Monthly 1985 June-July issue
If the ancient Greeks had not been distracted by
investigations of triangular (as opposed to square )
numbers, they might have done something with this fact.
A search for occurrences of the phrase
"n2 [i.e., n 2 ] congruent triangles"
indicates only fairly recent (i.e., later than 1984) results.*
Some related material, updated this morning—
|
This suggests a problem—
What mappings of a square array of n 2 points to
In the figure above, whether |
* Update of July 15, 2012 (11:07 PM ET)—
Theorem on " rep-n 2 " (Golomb's terminology)
triangles from a 1982 book—
Comments Off on Not Quite Obvious
Saturday, July 7, 2012
Quartet
"Euclid (Ancient Greek: Εὐκλείδης Eukleidēs), fl. 300 BC,
also known as Euclid of Alexandria, was a Greek
mathematician, often referred to as the 'Father of Geometry.'"
— Wikipedia
A Euclidean quartet (see today's previous post)—
Image by Alexander Soifer
See also a link from June 28, 2012, to a University Diaries post
discussing "a perfection of thought."
Perfect means, among other things, completed .
See, for instance, the life of another Alexandrian who reportedly
died on the above date—
"Gabriel Georges Nahas was born in Alexandria, Egypt, on
March 4, 1920…."
— This afternoon's online New York Times
Comments Off on Quartet
Étude
For remarks related by logic, see the square-triangle theorem.
For remarks related by synchronicity, see Log24 on
the above publication date, June 15, 2010.
According to Google (and Soifer's page xix), Soifer wants to captivate
young readers.
Whether young readers should be captivated is open to question.
"There is such a thing as a 4-set."
Update of 9:48 the same morning—
Amazon.com says Soifer's book was published not on June 15, but on
June 29 , 2010
(St. Peter's Day).
Comments Off on Étude
Sunday, May 27, 2012
Finite Jest
The books pictured above are From Discrete to Continuous ,
by Katherine Neal, and Geometrical Landscapes , by Amir Alexander.
Commentary—
“Harriot has given no indication of how to resolve
such problems, but he has pasted in in English,
at the bottom of his page, these three enigmatic
lines:
‘Much ado about nothing.
Great warres and no blowes.
Who is the foole now?’
Harriot’s sardonic vein of humour, and the subtlety of
his logical reasoning still have to receive their full due.”
— “Minimum and Maximum, Finite and Infinite:
Bruno and the Northumberland Circle,” by Hilary Gatti,
Journal of the Warburg and Courtauld Institutes ,
Vol. 48 (1985), pp. 144-163
Comments Off on Finite Jest
Thursday, March 22, 2012
Square-Triangle Theorem continued
Last night's post described a book by Alexander Soifer
on questions closely related to— and possibly
suggested by— a Miscellanea item and a letter to
the editor in the American Mathematical Monthly ,
June-July issues of 1984 and 1985.
Further search yields a series of three papers by
Michael Beeson on the same questions. These papers are
more mathematically presentable than Soifer's book.
Triangle Tiling I —
http://www.michaelbeeson.com/research/papers/TriangleTiling1.pdf
March 2, 2012
Triangle Tiling II —
http://www.michaelbeeson.com/research/papers/TriangleTiling2.pdf
February 18, 2012
Triangle Tiling III —
http://www.michaelbeeson.com/research/papers/TriangleTiling3.pdf
March 11, 2012
These three recent preprints replace some 2010 drafts not now available.
Here are the abstracts of those drafts—
"Tiling triangle ABC with congruent triangles similar to ABC"
(March 13, 2010),
"Tiling a triangle with congruent triangles"
(July 1, 2010).
Beeson, like Soifer, omits any reference to the "Triangles are square" item
of 1984 and the followup letter of 1985 in the Monthly .
Comments Off on Square-Triangle Theorem continued
Wednesday, March 21, 2012
Square-Triangle Theorem
(Continued from March 18, 2012)
Found in a search this evening—
How Does One Cut a Triangle? by Alexander Soifer
(Second edition, Springer, 2009. First edition published
by Soifer's Center for Excellence in Mathematical Education,
Colorado Springs, CO, in 1990.)
This book, of xxx + 174 pages, covers questions closely related
to the "square-triangle" result I published in a letter to the
editor of the June-July 1985 American Mathematical Monthly
(Vol. 92, No. 6, p. 443). See Square-Triangle Theorem.
Soifer's four pages of references include neither that letter
nor the Monthly item, "Miscellaneum 129: Triangles are square"
of a year earlier that prompted the letter.
Comments Off on Square-Triangle Theorem
Sunday, March 18, 2012
Square-Triangle Diamond
The diamond shape of yesterday's noon post
is not wholly without mathematical interest …
"Every triangle is an n -replica" is true
if and only if n is a square.
The 16 subdiamonds of the above figure clearly
may be mapped by an affine transformation
to 16 subsquares of a square array.
(See the diamond lattice in Weyl's Symmetry .)
Similarly for any square n , not just 16.
There is a group of 322,560 natural transformations
that permute the centers of the 16 subsquares
in a 16-part square array. The same group may be
viewed as permuting the centers of the 16 subtriangles
in a 16-part triangular array.
(Updated March 29, 2012, to correct wording and add Weyl link.)
Comments Off on Square-Triangle Diamond
Thursday, January 19, 2012
Square Triangles
MathWorld.Wolfram.com has an article titled "Square-Triangle Theorem."
An article of my own, whose HTML title was previously "Triangles are Square," has been retitled accordingly.
Comments Off on Square Triangles
Monday, January 16, 2012
Mapping Problem
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.
Here is a trial solution of the inverse problem—
Exercise— Devise a test for "naturality" of
such mappings and apply it to the above.
Comments Off on Mapping Problem
Thursday, January 12, 2012
Triangles Are Square
Coming across John H. Conway's 1991*
pinwheel triangle decomposition this morning—
|
|
— suggested a review of a triangle decomposition result from 1984:
Figure A
(Click the below image to enlarge.)
The above 1985 note immediately suggests a problem—
What mappings of a square with c 2 congruent parts
to a triangle with c 2 congruent parts are "natural"?**
(In Figure A above, whether the 322,560 natural transformations
of the 16-part square map in any natural way to transformations
of the 16-part triangle is not immediately apparent.)
* Communicated to Charles Radin in January 1991. The Conway
decomposition may, of course, have been discovered much earlier.
** Update of Jan. 18, 2012— For a trial solution to the inverse
problem, see the "Triangles are Square" page at finitegeometry.org.
Comments Off on Triangles Are Square
Thursday, May 22, 2008
Thursday May 22, 2008
841: Dublin founded by
Danish [?] Vikings
9/04: In a Nutshell: The Seed
Danish [?] Vikings
9/04: In a Nutshell: The Seed
(See also Hamlet’s Transformation.)
The moral of this story,
it’s simple but it’s true:
Hey, the stars might lie,
but the numbers never do.
Comments Off on Thursday May 22, 2008