Log24

On the feast of Saint Nicholas

See also the six  posts on this year's feast of Saint Andrew
and the following from the University  of St. Andrews —

Click for a larger image. 

For a different pictorial approach, see Polster's
1998 Geometrical Picture Book , pp. 77-80.

Update:  Added to finitegeometry.org on Jan. 2, 2014.
(The source of the images of the 35 lines was the image
"Geometry of the Six-Element Set," with, in the final two
of the three projective-line parts, the bottom two rows
and the rightmost two columns interchanged.)

The title is taken from a book for ages 8-12 published
on Shakespeare's birthday, April 23, 2013.

Also from that date, a note for older readers—

… Half a dozen of the other —

For further context, see all  posts for the cruelest month of this past year.

* Secrets :  A sometimes dangerous word.

From a review of Truth and Other Enigmas , a book by the late Michael Dummett—

"… two issues stand out as central, recurring as they do in many of the
essays. One issue is the set of debates about realism, that is, those debates that ask
whether or not one or another aspect of the world is independent of the way we
represent that aspect to ourselves. For example, is there a realm of mathematical
entities that exists fully formed independently of our mathematical activity? Are
there facts about the past that our use of the past tense aims to capture? The other
issue is the view— which Dummett learns primarily from the later Wittgenstein—
that the meaning of an expression is fully determined by its use, by the way it
is employed by speakers. Much of his work consists in attempts to argue for this
thesis, to clarify its content and to work out its consequences. For Dummett one
of the most important consequences of the thesis concerns the realism debate and
for many other philosophers the prime importance of his work precisely consists
in this perception of a link between these two issues."

— Bernhard Weiss, pp. 104-125 in Central Works of Philosophy , Vol. 5,
ed. by John Shand, McGill-Queen's University Press, June 12, 2006

The above publication date (June 12, 2006) suggests a review of other
philosophical remarks related to that date. See …

• a June 12, 2006 link (in a 2007 post) to Geometry of the 4×4 Square,
• some related remarks on Dummett and Universals in this journal, and
• the following excerpt from Spekkens's toy model—

  "Every partitioning of the set of sixteen ontic states
  into four disjoint pure epistemic states
  yields a maximally informative measurement."—

For some more-personal remarks on Dummett, see yesterday afternoon's
"The Stone" weblog in The New York Times.

I caught the sudden look of some dead master….

— Four Quartets

Page 67 —

“… Bill and Violet were married. The wedding was held in the Bowery loft on June 16th, the same day Joyce’s Jewish Ulysses had wandered around Dublin. A few minutes before the exchange of vows, I noted that Violet’s last name, Blom, was only an o away from Bloom, and that meaningless link led me to reflect on Bill’s name, Wechsler, which carries the German root for change, changing, and making change. Blooming and changing, I thought.”

For Hustvedt’s discussion of Wechsler’s art– sculptured cubes, which she calls “tightly orchestrated semantic bombs” (p. 169)– see Log24, May 25, 2008.

Related 3×3 patterns appear
in “nine-patch” quilt blocks
and in the following–

Jared Tarbell at levitated.net, May 15, 2002: “The nine block is a common design pattern among quilters. Its construction methods and primitive building shapes are simple, yet produce millions of interesting variations. Figure A. Four 9 block patterns, arbitrarily assembled, show the grid composition of the block. Each block is composed of 9 squares, arranged in a 3 x 3 grid. Each square is composed of one of 16 primitive shapes. Shapes are arranged such that the block is radially symmetric. Color is modified and assigned arbitrarily to each new block. The basic building blocks of the nine block are limited to 16 unique geometric shapes. Each shape is allowed to rotate in 90 degree increments. Only 4 shapes are allowed in the center position to maintain radial symmetry. Figure B. The 16 possible shapes allowed for each grid space. The 4 shapes allowed in the center have bold numbers.”

   
Such designs become of mathematical interest when their size is increased slightly, from square arrays of nine blocks to square arrays of sixteen.  See Block Designs in Art and Mathematics.

(This entry was suggested by examples of 4×4 Identicons in use at Secret Blogging Seminar.)

"[The applet] Syntheme illustrates ways of partitioning the 12 vertices of an icosahedron into 3 sets of 4, so that each set forms the corners of a rectangle in the Golden Ratio. Each such rectangle is known as a duad. The short sides of a duad are opposite edges of the icosahedron, and there are 30 edges, so there are 15 duads.

Each partition of the vertices into duads is known as a syntheme. There are 15 synthemes; 5 consist of duads that are mutually perpendicular, while the other 10 consist of duads that share a common line of intersection."

— Greg Egan, Syntheme

The above note shows
duads and synthemes related
to the diamond theorem.

See also John Baez's essay
"Some Thoughts on the Number 6."
That essay was written 15 years
ago today– which happens
to be the birthday of
Sir Laurence Olivier, who,
were he alive today, would
be 100 years old.

"Is it safe?"

Beyond Geometry

(Title of current L. A. art exhibit)

“The greatest obstacle to discovery
is not ignorance —
  it is the illusion of knowledge.”

Mental Health Month, Day 26:

Many Dimensions,

Part III — Why 26?

At first blush, it seems unlikely that the number 26=2×13, as a product of only two small primes (and those distinct) has any purely mathematical properties of interest. (On the other hand, consider the number 6.)  Parts I and II of “Many Dimensions,” notes written earlier today, deal with the struggles of string theorists to justify their contention that a space of 26 dimensions may have some significance in physics.  Let them struggle.  My question is whether there are any interesting purely mathematical properties of 26, and it turns out, surprisingly, that there are some such properties. All this is a longwinded way of introducing a link to the web page titled “Info on M13,” which gives details of a 1997 paper by J. H. Conway*.

There is no obvious connection to physics, although the physics writer John Baez quoted in my previous two entries shares Conway’s interest in the Mathieu groups. 

 * J. H. Conway, “M₁₃,” in Surveys in Combinatorics, 1997, edited by R. A. Bailey, London Mathematical Society Lecture Note Series, 241, Cambridge University Press, Cambridge, 1997. 338 pp. ISBN 0 521 59840 0.