A space where author Madeleine L'Engle worked as a librarian —
A more abstract space —
"If you have built castles in the air, your work need not be lost;
that is where they should be. Now put the foundations under them.”
— Henry David Thoreau
260731-Fano-1892-PG(3,2)…AI_Overview.jpg
...AI_Overview.jpg)
260731-Square_Model_of_PG(3,2)-by-Cullinane…AI_Overview.jpg
-by-Cullinane...AI_Overview.jpg)
* See Kirkman's schoolgirl problem in Wikipedia, esp.
the sections "Galois Geometry" and "Spreads and Packing."
The geometry of what might be called "Schoolgirl Space"
is, as the above image "Geometry of the Six Element Set"
indicates, the same as the geometry of the "Hexastigm"
described by Richmond (King's College, Cambridge,
March 30, 1899) —
"On the Figure of Six Points in Space of Four Dimensions,"
by H. W. Richmond, Quarterly Journal of Pure and Applied
Mathematics, Vol. 31 (1900), pp. 125-160.
This is available on the Web at Scribd.com . . .
https://www.scribd.com/document/424182244/
Richmond-QuarterlyJournal-1900-SixPoints .
Richmond's excellent historical survey, together with the Cullinane
square model of PG(3,2), provide the connection of finite geometry
to earlier, non-finite geometry that is lacking in some later treatments
of the subject . . . in particular, the connection to finite geometry of
studies of the classical sixty Pascal lines of the Hexagrammum.
From posts tagged Schoolgirl Space —
As for Epstein’s problem . . .
Underlying Structure of the Design —
Schoolgirl Problem —
"Old men ought to be explorers." — T. S. Eliot.
Rose the Hat in her younger days.
See as well Barsotti in this journal.
The 15 points of the finite projective 3-space PG(3,2)
arranged in tetrahedral form:
The letter labels, but not the tetrahedral form,
are from The Axioms of Projective Geometry , by
Alfred North Whitehead (Cambridge U. Press, 1906).
The above space PG(3,2), because of its close association with
Kirkman's schoolgirl problem, might be called "schoolgirl space."
Screen Rant on July 31, 2019:
A Google Search sidebar this morning:
Apocalypse Soon! —
The exercise in the previous post was suggested by a passage
purporting to "use standard block design theory" that was written
by some anonymous author at Wikipedia on March 1, 2019:
Here "rm OR" apparently means "remove original research."
Before the March 1 revision . . .
The "original research" objected to and removed was the paragraph
beginning "To explain this further." That paragraph was put into the
article earlier on Feb. 28 by yet another anonymous author (not by me).
An account of my own (1976 and later) original research on this subject
is pictured below, in a note from Feb. 20, 1986 —
The Square "Inscape" Model of
the Generalized Quadrangle W(2)
Click image to enlarge.
-embedding-in-PG(3,2)-Planat-Saniga-1000w.jpg)
* The title refers to the role of PG (3,2) in Kirkman's schoolgirl problem.
For some backstory, see my post Anticommuting Dirac Matrices as Skew Lines
and, more generally, posts tagged Dirac and Geometry.
From Dan Brown's novel Angels & Demons (2000)—
Cube Bricks 1984 —
From "Tomorrowland" (2015) —
From John Baez (2018) —
See also this morning's post Perception of Space
and yesterday's Exploring Schoolgirl Space.
See also "Quantum Tesseract Theorem" and "The Crosswicks Curse."
Anonymous remarks on the schoolgirl problem at Wikipedia —
"This solution has a geometric interpretation in connection with
Galois geometry and PG(3,2). Take a tetrahedron and label its
vertices as 0001, 0010, 0100 and 1000. Label its six edge centers
as the XOR of the vertices of that edge. Label the four face centers
as the XOR of the three vertices of that face, and the body center
gets the label 1111. Then the 35 triads of the XOR solution correspond
exactly to the 35 lines of PG(3,2). Each day corresponds to a spread
and each week to a packing."
See also Polster + Tetrahedron in this journal.
There is a different "geometric interpretation in connection with
Galois geometry and PG(3,2)" that uses a square model rather
than a tetrahedral model. The square model of PG(3,2) last
appeared in the schoolgirl-problem article on Feb. 11, 2017, just
before a revision that removed it.
The dies natalis of St. Buddy Holly was Feb. 3, 1959.
This year on Feb. 3, a geometric illustration of the well-known
schoolgirl problem was added to a brand-new Wikipedia article
on the finite geometry PG(3,2).
A Warren, Pennsylvania, newspaper article from May 12, 2018,
“A terrorist among them,” quotes Ann Creal of Warren on
schooldays of the late 1950’s and on a German exchange student,
Gudrun Ensslin, who later became famous for her violent political
activities:
“She said Ensslin dated while here (the man
she identified as Ensslin’s date told the Times Observer
he had no recollection of her).”
I am the man that was identified as Ensslin’s date, and I still
have no recollection of her.
Ann Creal is the former Ann Fuellhart, who was a college freshman
in the fall of 1959, when I was a high school senior —
Ann Creal apparently confused me with Scott Mohr, who
graduated from Warren High School in 1958. See the Log24
posts Crux and Doppelgänger.
A Feb. 12 note in the "talk" section of the Wikipedia article
"Kirkman's schoolgirl problem" —
The illustration above was replaced by a new section in the article,
titled "Galois geometry."
The new section improves the article by giving it greater depth.
For related material, see Conwell Heptads in this journal
(or, more generally, Conwell) and a 1985 note citing Conwell's work.
Compare and contrast the recent films
"The Diary of a Teenage Girl" and "Strangerland."
(This post was suggested by yesterday's
"How Deep the Rabbit Hole Goes.")
and versions of "Both Sides Now"
See a New York Times version of "Both Sides Now."
I prefer a version by Umberto Eco.
Related material for storytellers and the Church of Synchronology —
This journal on the date of the above shooting script, 03/19/15.
Or: Ten Years and a Day
In memory of film director Robert Wise,
who died ten years ago yesterday.
A search in this journal for "Schoolgirl" ends with a post
from Sept. 10, 2002, The Sound of Hanging Rock.
See as well a Log24 search for "Strangerland"
(a 2015 film about a search for a schoolgirl) and
a Log24 search for "Weaving."
Related mathematics: Symplectic.
Some related images (click to enlarge) —
But first, a word from our sponsa* …
Sir Laurence Olivier in "Term of Trial" (1962),
a film starring Sarah Miles as a schoolgirl —
* Bride in Latin. See also "bride's chair,"
a phrase from mathematical pedagogy.
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