The Universe of Discourse

Mark Dominus (陶敏修)
mjd@pobox.com

12 recent entries

Stuff that is and isn't backwards in Australia
3-coloring the vertices of an icosahedron
Stuff that is backwards in Australia
Werewolf ammunition
Optimal boxes with and without lids
Children and adults see in very different ways
Even without an alien invasion, February 22 on Talos I would have been a shitshow
Etymology roundup 2024-02
The pleasures of dolmen-licking
Jehovah's Witnesses do not number the days of the week
My Git pre-commit hook contained a footgun
Recent addenda to articles 202311: Christenings in Tel Aviv

Archive:

2024: JF M A
2023: JF M A M J
J A S O N D
2022: J F M A M J
JAS O N D
2021: J F M AMJ
J A S O N D
2020: J F M A M J
J A S O N D
2019: JFM A M J
J A S O N D
2018: J F M A M J
J A S O N D
2017: J F M A M J
J A S O N D
2016: JF M A M J
JASON D
2015: JFM A M J
J A S O N D
2014: J F M AMJ
JASON D
2013: JFMAMJ
JAS OND
2012: J F MAMJ
JASOND
2011: JFMAM J
JASOND
2010: JFMAMJ
JA S O ND
2009: J F MAM J
JASOND
2008: J F M A M J
JAS O ND
2007: J F M A M J
J A S O N D
2006: J F M A M J
JAS O N D
2005: O N D

Subtopics:

Mathematics 238

Programming 99

Language 92

Miscellaneous 67

Book 49

Tech 48

Etymology 34

Haskell 33

Oops 30

Unix 27

Cosmic Call 25

Math SE 23

Physics 21

Law 21

Perl 17

Biology 15

Comments disabled

Sat, 30 May 2020

Addendum: optical illusion

John Gleeson points out that my optical illusion (below left) appears to be a variation on the classic Poggendorff illusion (below right):

A circle, with the
center marked. A shortest-distance path is drawn in blue between two
blue points on the same radius, and in red between two red points on different
radii. The blue path goes straight from one blue point to the other.
The red path goes from one point straight to the origin,
then straight to the other point.

A narrow gray rectangle,
with a black line proceeding from the upper left to disappear behind
it, and parallel red and blue lines emerging from behind it to
continue to the lower right. It appears that if the black line were
extended it would coincide with the blue one, but a second version of
the diagram, where the gray rectangle has been rendered
semitransparent, reveals that the blak line actually coincides with
the red one. By Fibonacci. - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2073873

[Other articles in category /brain] permanent link