Category: Geometry Page 5 of 168
Seven years ago in this journal — The above links: the Stone, the rules.
Holy Saturday is, according to tradition, the day of the harrowing of Hell. Notes: The above passage on "Die Figuren der vier Modi im Magischen Quadrat " should be…
Continued from yesterday, the date of death for German billionaire philanthropist Klaus Tschira — For Tschira in this journal, see Stiftung . For some Würfel illustrations, see this morning's post Manifest O. A…
The title was suggested by http://benmarcus.com/smallwork/manifesto/. The "O" of the title stands for the octahedral group. See the following, from http://finitegeometry.org/sc/map.html — 83-06-21 An invariance of symmetry The diamond theorem on a…
The incidences of points and planes in the Möbius 84 configuration (8 points and 8 planes, with 4 points on each plane and 4 planes on each point), were described by Coxeter in…
(Continued from July 16, 2014.) Some background from Wikipedia: "Friedrich Ernst Peter Hirzebruch ForMemRS[2] (17 October 1927 – 27 May 2012) was a German mathematician, working in the fields of topology, complex…
Yesterday's post suggests a review of the following — Andries Brouwer, preprint, 1982: "The Witt designs, Golay codes and Mathieu groups" (unpublished as of 2013) Pages 8-9: Substructures…
From H. S. M. Coxeter's 1950 paper "Self-Dual Configurations and Regular Graphs," a 4×4 array and a more perspicuous rearrangement— (Click image to enlarge.) The above rearrangement brings Coxeter's…
A sequel to Dude! See also "Triangles are Square."