The Pentagrammum Mysticum, Twelve Special Conics and the Twisted Icosahedron
Journal for geometry and graphics, Tome 24 (2020) no. 2, pp. 175-191
We study an abstract pentagon in planar projective geometry via its unique circumscribing conic, associated to 15 diagonal lines and exagonal points, and describe 12 beautifully inter-related conics. These are closely connected to a distance-regular graph X which is a sister of the icosahedral graph, arising from dihedral orderings of five objects.
Classification :
14Nxx, 51A20, 05Exx
Mots-clés : Strongly regular graph, icosahedron, Pascal theorem, conic, pentagon
Mots-clés : Strongly regular graph, icosahedron, Pascal theorem, conic, pentagon
@article{JGG_2020_24_2_JGG_2020_24_2_a2,
author = {N. Le and N. J. Wildberger},
title = {The {Pentagrammum} {Mysticum,} {Twelve} {Special} {Conics} and the {Twisted} {Icosahedron}},
journal = {Journal for geometry and graphics},
pages = {175--191},
year = {2020},
volume = {24},
number = {2},
url = {http://geodesic.mathdoc.fr/item/JGG_2020_24_2_JGG_2020_24_2_a2/}
}
TY - JOUR AU - N. Le AU - N. J. Wildberger TI - The Pentagrammum Mysticum, Twelve Special Conics and the Twisted Icosahedron JO - Journal for geometry and graphics PY - 2020 SP - 175 EP - 191 VL - 24 IS - 2 UR - http://geodesic.mathdoc.fr/item/JGG_2020_24_2_JGG_2020_24_2_a2/ ID - JGG_2020_24_2_JGG_2020_24_2_a2 ER -
N. Le; N. J. Wildberger. The Pentagrammum Mysticum, Twelve Special Conics and the Twisted Icosahedron. Journal for geometry and graphics, Tome 24 (2020) no. 2, pp. 175-191. http://geodesic.mathdoc.fr/item/JGG_2020_24_2_JGG_2020_24_2_a2/