Log24

Friday, February 21, 2020

Frozen

Filed under: General — Tags: — m759 @ 12:30 PM

Thursday, February 20, 2020

In Memory of Jack Youngerman…

Filed under: General — Tags: — m759 @ 11:54 PM

An abstract artist who reportedly died at 93 yesterday.

A search in this  journal for Shubnikov yields

"Raiders of the Lost Stone" (December 26, 2017).

Once Upon a Time in Las Vegas

Filed under: General — Tags: — m759 @ 4:25 PM

Wheel Turnin’ ’Round and ’Round

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

Wednesday, February 19, 2020

Aitchison’s Octads

Filed under: General — Tags: , — m759 @ 11:36 AM

The 759 octads of the Steiner system S(5,8,24) are displayed
rather neatly in the Miracle Octad Generator of R. T. Curtis.

A March 9, 2018, construction by Iain Aitchison* pictures the
759 octads on the faces of a cube , with octad elements the
24 edges of a  cuboctahedron :

The Curtis octads are related to symmetries of the square.

See my webpage "Geometry of the 4×4 square" from March 2004.
Aitchison's p. 42 slide includes an illustration from that page —

Aitchison's  octads are instead related to symmetries of the cube.

Note that essentially the same model as Aitchison's can be pictured 
by using, instead of the 24 edges of a cuboctahedron, the 24 outer 
faces of subcubes in the eightfold cube .

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

   Image from Christmas Day 2005.

http://www.math.sci.hiroshima-u.ac.jp/branched/files/2018/
presentations/Aitchison-Hiroshima-2-2018.pdf
.
See also Aitchison in this journal.

 
 

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