Log24

Wednesday, January 1, 2025

Square Triangles for Doctor Faustus

Filed under: General — Tags: , — m759 @ 11:20 pm

Symmetry in 'Magic Square' Triangles

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?

Thursday, January 19, 2012

Square Triangles

Filed under: General,Geometry — Tags: , — m759 @ 1:26 pm

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.

Friday, May 20, 2022

Squares to Triangles

Filed under: General — Tags: , , , , — m759 @ 11:24 am

(Continued)

Related concepts: Steiner system, Affine transformation, Square triangle.

Thursday, January 12, 2012

Triangles Are Square

Filed under: General,Geometry — Tags: , , , — m759 @ 11:30 am

Coming across John H. Conway's 1991*
pinwheel  triangle decomposition this morning—

http://www.log24.com/log/pix12/120112-ConwayTriangleDecomposition.jpg

— suggested a review of a triangle decomposition result from 1984:

IMAGE- Triangle and square, each with 16 parts

Figure A

(Click the below image to enlarge.)

IMAGE- 'Triangles Are Square,' by Steven H. Cullinane (American Mathematical Monthly, 1985)

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.

Saturday, April 25, 2026

Finite Geometry of the Square and Triangle

Filed under: General — Tags: — m759 @ 8:57 am
 

Two facts from figurate geometry . . .

Taken together, these imply that a geometric object 
(such as the Steiner system S (5, 8, 24))
with p2-1 (= (p-1)(p+1)) points, where p >3 is a prime, 
can be pictured as a six-part triangular array with one point
removed. If the point removed is at the center, it may happen
that such an array can be split (in various ways) into six parts
(a sextet , in the case of S (5, 8, 24)),
each with the same number of subtriangles, that form symmetric  
patterns more readily than corresponding six-part arrangements
within a square  array (with one point removed).

(Of course, for S (5, 8, 24),  a hexagonal  arrangement of six
equilateral triangles, each subdivided into four triangular parts, 
may offer better opportunities for subgroup actions preserving symmetry.)

Saturday, September 10, 2022

Orthogonal Latin Triangles

Filed under: General — Tags: , , — m759 @ 1:38 am

From a 1964 recreational-mathematics essay —

Note that the first two triangle-dissections above are analogous to
mutually orthogonal Latin squares . This implies a connection to
affine transformations within Galois geometry. See triangle graphics
in this  journal.

Affine transformation of 'magic' squares and triangles: the triangle Lo Shu 

Update of 4:40 AM ET —

Other mystical figures —

Magic cube and corresponding hexagram, or Star of David, with faces mapped to lines and edges mapped to points

"Before time began, there was the Cube."

— Optimus Prime in "Transformers" (Paramount, 2007)

Friday, August 13, 2021

The Divided Square

Filed under: General — Tags: , , — m759 @ 12:19 am

Compare and contrast —

Update of 2:25 PM ET on Friday, August 13th, 2021 —

Plato's alleged motto, "Let no one ignorant of geometry enter,"
seems to have been of little use to those attempting to make sense
of his "divided line" analogy in the Republic.

Some related geometry —

    The Divided Square :

Three Similarly Divided Squares :

The image “http://www.log24.com/log/pix06A/Pythagorean_Theorem.jpg” cannot be displayed, because it contains errors.

Scholium —

Thursday, February 13, 2020

Square-Triangle Mappings: The Continuous Case

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

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."

Sunday, July 15, 2012

Squares Are Triangular

Filed under: General,Geometry — Tags: , , — m759 @ 2:00 pm

"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—

IMAGE- 16 points in a square array and in a triangular array

Call a convex polytope P  an n-replica  if  P  consists of
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

Triangles Are Square.

Thursday, March 22, 2012

Square-Triangle Theorem continued

Filed under: General,Geometry — Tags: , — m759 @ 6:00 am

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 .

Wednesday, March 21, 2012

Square-Triangle Theorem

Filed under: General,Geometry — Tags: , , — m759 @ 10:30 pm

(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.

Sunday, March 18, 2012

Square-Triangle Diamond

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

The diamond shape of yesterday's noon post
is not wholly without mathematical interest …

The square-triangle theorem

"Every triangle is an n -replica" is true
if and only if n  is a square.

IMAGE- Square-to-diamond (rhombus) shear in proof of square-triangle theorem

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.)

Thursday, February 13, 2025

The Exploitation of Symmetry . . . Continues.

Filed under: General — Tags: , — m759 @ 2:51 pm

Illustration of a July 1980 title by George Mackey

Exploitation of Symmetry in 1981 . . .

See also the tetrahedra* in my "square triangles" letter
(1985), as well as "Senechal" in this  journal.

"And we both know what memories can bring…"  Do we?

* "Schläfli orthoschemes"

Saturday, November 2, 2024

For Julia Cicero:  Ex Fano Apollinis

Filed under: General — Tags: — m759 @ 11:56 pm

Cicero, In Verrem  II. 1. 46 —

He reached Delos. There one night he secretly   46 
carried off, from the much-revered sanctuary of 
Apollo, several ancient and beautiful statues, and 
had them put on board his own transport. Next 
day, when the inhabitants of Delos saw their sanc- 
tuary stripped of its treasures, they were much 
distressed . . . .
Delum venit. Ibi ex fano Apollinis religiosissimo 
noctu clam sustulit signa pulcherrima atque anti- 
quissima, eaque in onerariam navem suam conicienda 
curavit. Postridie cum fanum spoliatum viderent ii 

See also "Ex Fano" in this  journal.

For more crazed gravitas, vide . . .

Latin Square Triangles .


Addendum:

The above New Yorker  passage is dated Sept. 26, 2024.
Also on that date . . .

Tuesday, May 31, 2022

A Mad Night’s Work*

Filed under: General — Tags: , — m759 @ 8:57 am

Last night's posts on triangles, and today's anniversary of the
death of Evariste Galois, suggest a review . . .

"Take triangles, perhaps" . . . as a category.

And then . . . take squares, perhaps, as another category, 
and then . . . find a suitable "translation machine."

See "Square Triangles."

* Title adapted from a 2001 essay by Pierre Cartier.

Tuesday, September 10, 2019

Congruent Subarrays

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

A search for "congruent subarrays" yields few results. Hence this post.

Some relevant mathematics:  the Cullinane diamond theorem, which
deals with permutations  of congruent subarrays.

A related topic:  Square Triangles (December 15, 2015).

Sunday, April 15, 2018

Colorado Olympiad

Filed under: General,Geometry — Tags: — m759 @ 1:01 pm

Or:  Personalities Before Principles

Personalities —

Principles —

This  journal on April 28, 2004 at 7:00 AM.

Backstory —

Square Triangles in this journal.

Friday, May 15, 2026

Bar Wars . . . Boogie Night AI

Filed under: General — Tags: , , — m759 @ 12:39 am
 

The Bar:

Alternate "Dog Years" title — "The Last Movie Star" —


 

The Mitzvah:

Affine transformation of 'magic' squares and triangles: the triangle Lo Shu

Wednesday, April 29, 2026

The AI in the Pyramid —
Brutalist Verhexung

Filed under: General — Tags: , , — m759 @ 10:59 am

"Die Philosophie ist ein Kampf gegen die Verhexung
unsres Verstandes durch die Mittel unserer Sprache."

— Wittgenstein, Philosophical Investigations  (1953),  
Section 109

Google AI Mode, April 28, 2026 —

"An equilateral triangle subdivided into n 2 congruent triangles
has a central sub-triangle if and only if n  is a multiple of 3
(n ≡ 0 (mod 3))."

Refutation —

Tuesday, April 28, 2026

A Socratic Torpedo — Six … Seven!

Filed under: General — Tags: — m759 @ 1:11 am

Saturday, April 25, 2026

The Verhexung Confrontation*

Filed under: General — Tags: , — m759 @ 9:37 pm

"Die Philosophie ist ein Kampf gegen die Verhexung
unsres Verstandes durch die Mittel unserer Sprache."

— Wittgenstein, Philosophical Investigations  (1953),  
Section 109

The "Tetragrammaton of Pythagoras" —

"Duck Soup" fans may recall the war between Freedonia and Sylvania.

For some images more in the spirit of Sylvania, see "Triangles Are Square."

* The word "confrontation" was suggested by the previous post.

ABC Art

Filed under: General — Tags: , — m759 @ 10:06 am

On  the  Netflix  series  "Maniac" —

"The treatment Owen and Annie sign up for promises to fix
its subjects’ brains with just three little pills—A, B, and C—
administered one after another over the span of three days.
The first forces you to relive your trauma;
the second exposes your blind spots; and
the third pill forces a confrontation."

— Kara Weisenstein at vice.com, Sept. 26, 2018, 12:19 PM

C — Saturday, April 25, 2026

Two facts from figurate geometry . . .

Taken together, these imply that a geometric object 
(such as the Steiner system S (5, 8, 24))
with p2-1 (= (p-1)(p+1)) points, where p >3 is a prime, 
can be pictured as a six-part triangular array with one point
removed. If the point removed is at the center, it may happen
that such an array can be split (in various ways) into six parts
(a sextet , in the case of S (5, 8, 24)),
each with the same number of subtriangles, that form symmetric  
patterns more readily than corresponding six-part arrangements
within a square  array (with one point removed).

(Of course, for S (5, 8, 24),  a hexagonal  arrangement of six
equilateral triangles, each subdivided into four triangular parts, 
may offer better opportunities for subgroup actions preserving symmetry.)

— Friday, April 24, 2026

A — Thursday, April 23, 2026

Monday, April 20, 2026

NotebookLM Report:  Grid as Portal

Filed under: General — Tags: — m759 @ 11:03 am
 

Mapping the Infinite: A Visual Guide
to the Cullinane Diamond Theorem

[ NotebookLM report on April 20, 2026 ]

1. The Canvas: The 4×4 Diamond Figure (D)

Welcome, fellow explorers of the visible and the abstract. Our journey into the heart of finite geometry begins with a deceptively simple object: the Diamond Figure D. Far from being a mere decorative motif, this grid serves as a portal—a visual coordinate system for a high-dimensional universe that otherwise remains hidden from the naked eye.

Figure D is defined by three essential physical characteristics:

  • The 16-Tile Array: A 4×4 square grid comprising 16 individual square cells.
  • The Diagonal Split: Every single square tile is divided diagonally into two distinct triangles.
  • The Two-Color System: A binary coloring scheme (typically black and white) is applied to the triangles, creating a directional "diamond" or "chevron" tension.

This specific configuration is the "key" to unlocking deep mathematics because it forces abstract algebraic structures into the open. By dividing the cells diagonally, we create a visual language that responds to movement and rotation, allowing us to "see" the properties of a finite field through the interplay of light and shadow.

As we look upon this static grid, realize that it is but a single state in a vast ocean of possibilities. To understand its true nature, we must set the grid in motion.

——————————————————————————–

2. The Engine of Transformation: Group G and Symmetry Invariance

When we rearrange this 4×4 grid, we are not simply playing with tiles; we are invoking the power of Group G. This mathematical engine is isomorphic to AGL(4,2)—the full affine group of a 4-dimensional vector space over the field of two elements. It consists of a staggering 322,560 distinct permutations.

These transformations are built from three primary rules:

Primary Transformation Rule

Description

Permutations of Rows

Any of the four rows may be swapped or rearranged in any of the 4! possible ways.

Permutations of Columns

Any of the four columns may be swapped or rearranged in any of the 4! possible ways.

Permutations of Quadrants

The grid's four 2×2 blocks (quadrants) can be swapped or permuted as independent units.

The "So What?" of the Diamond Theorem The revelation of Steven Cullinane’s theorem is its absolute Symmetry Invariance. No matter which of the 322,560 scrambles you apply, the resulting image always retains a discernible structure. It is never a random mess. Specifically, every G-image of D exhibits either:

  1. Ordinary Geometric Symmetry: Standard rotational or reflectional symmetry.
  2. Color-Interchange Symmetry: A property where the pattern remains identical if you swap all black sections for white and vice versa.

These 2D shuffles are actually the "shadows" of a higher-dimensional origin, acting as a flat projection of a four-dimensional world.

——————————————————————————–

3. Dimensional Collapse: From 3D Cubes to 2D Arrays

To truly "grok" the Diamond Theorem, we must view the 16 cells of the grid as witnesses to 4-dimensional symmetry. The 4×4 grid is a "dimensional collapse" of a tesseract (a 4D hypercube) onto a flat surface.

The Steps of Dimensional Mapping:

  1. Labeling with Affine 4-Space: We label each cell with a point from the affine 4-space over the finite field GF(2).
  2. Binary Positioning: Coordinates (0 and 1) are assigned to represent positions across four dimensions.
  3. The Hypercube Map: The 16 vertices of a tesseract are mapped directly onto the 16 cells of the square array.

The Parallelogram Rule of Vector Addition In this 4×4 space, geometry and algebra become one through the Parallelogram Rule. In a standard 3D space, if you have two vectors u and v, their sum w = u + v forms the diagonal of a parallelogram. On our 4×4 grid, this manifests visually: picking any two "direction" vectors automatically defines a third vertex. This means that vector addition in 4D space is performed directly on the grid; the "sum" of two cells is always another specific cell, maintaining a perfect triangular closure within the array.

This mapping turns a difficult-to-visualize 4D space into a visual "calculator" where geometric intuition replaces complex calculation.

——————————————————————————–

4. The Visual Language of Finite Fields: GF(16) and Binary XOR

The grid functions as a map of the finite field GF(16). Operations here utilize "Binary Addition," better known to computer scientists as the XOR operation (where 1 + 1 = 0).

The Zero-Sum Property and Closure Every pattern in this system can be decomposed into three "line diagrams." When these diagrams (D_1, D_2, D_3) are combined, they follow a strict "Zero-Sum" rule: D_1 + D_2 + D_3 = 0. In finite geometry, this represents the : if you have two points of a line, the third point is "forced" into existence to complete the set. The symmetry of the final pattern is inevitable because the algebra is perfectly balanced.

This visual language reveals the structure of the projective space PG(3,2):

  • The 15 Points: There are 15 possible basic line diagrams, representing the 15 points of the projective space.
  • The 35 Lines: The 840 distinct images produced by Group G fall into 35 families of patterns. Each family represents a "line" in the projective space—a set of three points that XOR to zero.

These abstract "lines" are not straight paths but families of symmetry, representing physical alignment and orthogonality in a finite world.

——————————————————————————–

5. Advanced Correspondences: Latin Squares and Skew Lines  [Table rewritten from NotebookLM version]

One of the most revolutionary aspects of the Diamond Theorem is how it bridges combinatorial puzzles and abstract geometry. Specifically, it provides a dictionary for "seeing" algebraic independence.

Within the 35 families of patterns, we find that exactly six special order-4 Latin squares have orthogonal mates. The theorem shows that the combinatorial "orthogonality" of these squares is actually a geometric property in disguise.

Combinatorial Term

Orthogonal Latin Squares

Superimposed grids showing every ordered pair of symbols exactly once.

Geometric Translation

Skew Lines in PG(3,2)

The Visual Outcome

Disjoint sets of line 
diagrams.

When a student sees that two patterns are "orthogonal," they are literally looking at skew lines—lines that exist in the same 3D projective space but never meet. Algebraic independence has never been more visible.

——————————————————————————–

6. The Tapestry of Application: From Quilts to Deep Space

The Cullinane Diamond Theorem proves that symmetry is not a decorative choice, but a mathematical inevitability found in everything from folk art to the stars.

  1. Quilt Design: Ancient artisans unintentionally utilized finite geometry. The theorem explains why traditional quilt blocks (like the "diamond" and "chevron") possess pervasive symmetry—they were tapping into the AGL(4,2) group without knowing it.
  2. The MOG & M24: The theorem is a visual sister to the Miracle Octad Generator (MOG). The symmetry group G is isomorphic to the octad stabilizer subgroup of the Mathieu group M_{24}, one of the mysterious sporadic simple groups.
  3. The Leech Lattice: These patterns serve as a visual bridge to the Leech Lattice, the most efficient way to pack spheres in 24 dimensions. The lattice is essentially a "blown-up" version of the Steiner system S(5,8,24) that governs these 4×4 symmetries.
  4. Coding Theory & Uninterrupted Cuts: The theorem is deeply linked to the Golay code, used by the Voyager probes to send clear images from deep space. Within the "Diamond Ring" of patterns, there exists an ideal of 1024 patterns characterized by "uninterrupted cuts" (where all horizontal or vertical lines remain unbroken). These patterns represent the peak of structural stability used in error-correcting codes.

——————————————————————————–

7. Summary Checklist for the Aspiring Learner

As you gaze upon the next 4×4 pattern you encounter, use this checklist to verify your understanding of the secrets "hidden in plain sight":

  • [ ] I understand that the 4×4 grid is a visual map of a 4-dimensional vector space.
  • [ ] I recognize that symmetry is preserved because the transformations are governed by the full affine group AGL(4,2).
  • [ ] I see that a "line" in this geometry is actually a family of three patterns that XOR to zero.
  • [ ] I can visualize the Parallelogram Rule, where adding two positions on the grid "forces" the third into existence.
  • [ ] I recognize the 1024 patterns with uninterrupted cuts as the mathematical "ideal" within the diamond ring.
  • [ ] I understand that orthogonal Latin squares are simply the visual manifestation of skew lines in projective space.

Keep your eyes open, for the infinite is often mapped onto the smallest of canvases.

Saturday, September 28, 2024

Architectural Singularity

Filed under: General — Tags: , — m759 @ 5:08 am

Embedded in the Sept. 26  New Yorker  review of Coppola's
Megalopolis is a ghostly transparent pyramidal figure . . .

The pyramidal figure is not unrelated to Scandia.tech

 

American Mathematical Monthly, Vol. 92, No. 6
(June-July 1985), p. 443

 

LETTERS TO THE EDITOR

Material  for this department should be prepared exactly the same way as submitted manuscripts (see the inside front cover) and sent to Professor P. R. Halmos, Department of Mathematics, University of Santa Clara, Santa Clara, CA 95053

Editor:

    Miscellaneum 129 ("Triangles are square," June-July 1984 Monthly ) may have misled many readers. Here is some background on the item.

    That n2 points fall naturally into a triangular array is a not-quite-obvious fact which may have applications (e.g., to symmetries of Latin-square "k-nets") and seems worth stating more formally. To this end, call a convex polytope P  an n-replica  if  P  consists of n mutually congruent polytopes similar to P  packed together. Thus, for n ∈ ℕ,

    (A) An equilateral triangle is an n-replica if and only if n is a square.

    Does this generalize to tetrahedra, or to other triangles? A regular tetrahedron is not a (23)-replica, but a tetrahedron ABCD  with edges AB, BC, and CD  equal and mutually orthogonal is an n-replica if and only if n is a cube. Every triangle satisfies the "if" in (A), so, letting T  be the set of triangles, one might surmise that

    (B) tT (t is an n-replica if and only if n is a square).

     This, however, is false. A. J. Schwenk has pointed out that for any m ∈ ℕ, the 30°-60°-90° triangle is a (3m2)-replica, and that a right triangle with legs of integer lengths a and b is an ((a+ b2)m2)-replica. As Schwenk notes, it does not seem obvious which other values of n can occur in counterexamples to (B). Shifting parentheses to fix (B), we get a "square-triangle" lemma:

    (C) ( tT, t  is an n-replica) if and only if n is a square.
   
    Miscellaneum 129 was a less formal statement of (C), with quotation marks instead of parentheses; this may have led many readers to think (B) was intended. To these readers, my apology.
 

Steven H. Cullinane      
501 Follett Run Road     
Warren, PA 16365         

Wednesday, July 31, 2024

My Links — Steven H. Cullinane

Filed under: — m759 @ 4:14 pm

Main webpage of record . . .

Encyclopedia of Mathematics  https://encyclopediaofmath.org/wiki/Cullinane_diamond_theorem

(A maintainable copy of that webpage was made by the Encyclopedia in 2026 at 
https://handwiki.org/wiki/Cullinane_diamond_theorem.)

Supplementary PDF from Jan. 6, 2006  https://encyclopediaofmath.org/images/3/37/Dtheorem.pdf

Originally published in paper version . . .

Computer Graphics and Art, 1978  http://finitegeometry.org/sc/gen/Diamond_Theory_Article.pdf
AMS abstract, 1979: "Symmetry Invariance in a Diamond Ring"  https://www.cullinane.design/
American Mathematical Monthly, 1984 and 1985: "Triangles Are Square"  http://finitegeometry.org/sc/16/trisquare.html

Personal sites . . .

Primary —

Personal journal   http://m759.net/wordpress/
Mathematics website  http://finitegeometry.org/sc/
Mathematics Images Gallery  http://m759.net/piwigo/index.php?/category/2

Secondary —

Portfoliobox   https://cullinane.pb.design/
Substack   https://stevenhcullinane.substack.com/  
Symmetry Summary   https://shc759.wordpress.com
Diamond Theory Cover Structure  https://shc7596.wixsite.com/website
3dthis.com  https://3dthis.com/profile.htm?owner=Cullinane
Latin Square Structure  https://shc7596.wixsite.com/website

SOCIAL:

Pinterest   https://www.pinterest.com/stevenhcullinane/ (many mathematics notes)
Flickr  https://www.flickr.com/photos/m759/ (backup account for images of mathematics notes)
Bluesky https://bsky.app/profile/m759.bsky.social
Instagram   https://www.instagram.com/stevencullinane
TikTok   https://www.tiktok.com/@stevenhcullinane
X.com   https://x.com/shc759

OTHER:

Replit viewer/download  https://replit.com/@m759/View-4x4x4?v=1
dSourceForge download  https://sourceforge.net/projects/finitegeometry/
Academia.edu   https://stevenhcullinane.academia.edu/
GitHub    https://github.com/m759 (finite geometry site download)
Internet Archive: Notes on Groups and Geometry   https://archive.org/details/NotesOnGroupsAndGeometry1978-1986/mode/2up         

Cited at  . . .

The Diamond Theorem and Truchet Tiles   http://www.log24.com/log22/220429-Basque-DT-1.pdf 
April 2024 UNION article in Spanish featuring the diamond theorem  https://union.fespm.es/index.php/UNION/article/view/1608/1214
April 2024 UNION article in English  http://log24.com/notes/240923-Ibanez-Torres-on-diamond-theorem-Union-April-2024-in-English.pdf
Cullinane in a 2020 Royal Holloway Ph.D. thesis   https://pure.royalholloway.ac.uk/ws/portalfiles/portal/40176912/2020thomsonkphd.pdf         
Squares, Chevrons, Pinwheels, and Bach   https://www.yumpu.com/en/document/read/36444818/fugue-no-21-elements-of-finite-geometry      
Observables  programmed presentation of diamond theorem  https://observablehq.com/@radames/diamond-theory-symmetry-in-binary-spaces
Josefine Lyche — Plato's Diamond  https://web.archive.org/web/20240222064628/http://www.josefinelyche.com/index.php?/selected-exhibitions/platos-diamond/
Josefine Lyche — Diamond Theorem  https://web.archive.org/web/20230921122049/http://josefinelyche.com/index.php?/selected-exhibitions/uten-ramme-nye-rom/

Professional sites . . .

Association for Computing Machinery   https://member.acm.org/~scullinane
bio.site/cullinane … maintenance at https://biosites.com
ORCID bio page   https://orcid.org/0000-0003-1135-419X
Google Scholar   https://scholar.google.com/citations?view_op=list_works&hl=en&hl=en&user=NcjmFwQAAAAJ&sortby=pubdate

Academic repositories:

Harvard Dataverse   https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/KHMMVH
Harvard DASH article on PG(3,2)   https://dash.harvard.edu/handle/1/37373777 

Zenodo website download  https://zenodo.org/records/1038121
Zenodo research notes  https://zenodo.org/search?q=metadata.creators.person_or_org.name%3A%22Cullinane%2C%20Steven%20H.%22&l=list&p=1&s=10&sort=bestmatch

Figurate Geometry at Open Science Framework (OSF)   https://osf.io/47fkd/

arXiv: "The Diamond Theorem"  https://arxiv.org/abs/1308.1075

AI reports:

NotebookLM: Diamond Theory  https://notebooklm.google.com/notebook/62ad8daa-277e-4fea-a680-9b209883f232?authuser=1

Microsoft Copilot Deep Research  https://www.log24.com/log25/2025-08-10-Copilot-Report-Cullinane-Diamond-Theorem.html

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.

Monday, March 11, 2024

Fundamental Figurate Geometry: Triangle Subdivision

Click to enlarge.

See as well "Triangles are Square," at
http://finitegeometry.org/sc/16/trisquare.html.

(I happened to find the Basu-Owen paper tonight
via a Google image search for "congruent subsets" . . .
as opposed to the "congruent subarrays" of
the previous post.)

Update of 3:54 PM ET Monday, March 11, 2024 —

This Stanford version of my square-to-triangle mapping
is the first publication in a new Zenodo community —

Citation for the research note:
Cullinane, Steven H. (2024). Fundamental Figurate Geometry:
Triangle Subdivision (Version 2). Zenodo.
https://doi.org/10.5281/zenodo.10822848
(latest version as of March 15, 2024)
 

Wednesday, February 28, 2024

A Definite School of Thought…
“The Buck Starts Here”

Filed under: General — Tags: , , — m759 @ 12:29 pm

https://theosophy.wiki/en/Jirah_Dewey_Buck

" Dr. Jirah Dewey Buck (November 20, 1838 – December 13, 1916)
was a physician who worked to establish one of the first Theosophical
lodges in the United States, the Cincinnati Theosophical Society, and
the American Section of the international Theosophical Society in 1886 . . . ."

"Buck was born in Fredonia, New York
on November 20, 1838 . . . .

[He was] 'a recognized leader of a definite school
of Masonic thought and propaganda'."

The above metadata was suggested by an image I happened to see today,
the "Tetragrammaton of Pythagoras" —

"Duck Soup" fans may recall the war between Freedonia and Sylvania.

For some images more in the spirit of Sylvania, see "Triangles Are Square."

Friday, September 22, 2023

Figurate Space

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

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.

Counting symmetries with the orbit-stabilizer theorem

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