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02 · First examples

G₁, G₂, G₃.

The segment and pentagon already display the self-dual pattern. In dimension three, the subdivision becomes genuinely spatial. The exact face-number pattern and its face lattices continue below.

PolytopeGeometryf-vectorMaximal-cell picture
G1Segment(1, 2, 1)2 verticesone interval
G2Pentagon(1, 5, 5, 1)5 verticessquare + triangle
G3Goodwillie polytope
(1, 12, 22, 12, 1)12 verticescube + 2 prisms + tetrahedron

The vectors include the empty face and the whole polytope. The cases n = 1, 2 are the formal extensions of the coordinate formula.

Exact face enumeration

The pattern beyond dimension three.

For 0 ≤ dn − 1, the proved formula is

fd(Gn) = 2n−1n+1d+1− 2nd−2n−1d+1− 2d−1n−1d−1.
PolytopeComplete f-vectorTotal faces
G1(1, 2, 1)4
G2(1, 5, 5, 1)12
G3(1, 12, 22, 12, 1)48
G4(1, 28, 73, 73, 28, 1)204
G5(1, 64, 215, 304, 215, 64, 1)864
G6(1, 144, 591, 1070, 1070, 591, 144, 1)3612
G7(1, 320, 1551, 3412, 4360, 3412, 1551, 320, 1)14928
G8(1, 704, 3935, 10178, 15764, 15764, 10178, 3935, 704, 1)61164
G9(1, 1536, 9727, 28912, 52528, 63616, 52528, 28912, 9727, 1536, 1)249024
G10(1, 3328, 23551, 79086, 164784, 233856, 233856, 164784, 79086, 23551, 3328, 1)1009212
G11(1, 7168, 56063, 209900, 493260, 801984, 939456, 801984, 493260, 209900, 56063, 7168, 1)4076208
G12(1, 15360, 131583, 543466, 1421860, 2604888, 3494304, 3494304, 2604888, 1421860, 543466, 131583, 15360, 1)16422924
G13(1, 32768, 305151, 1378280, 3973112, 8097056, 12233232, 14006784, 12233232, 8097056, 3973112, 1378280, 305151, 32768, 1)66045984
G14(1, 69632, 700415, 3434470, 10815688, 24268816, 40769872, 52564512, 52564512, 40769872, 24268816, 10815688, 3434470, 700415, 69632, 1)265246812
G15(1, 147456, 1593343, 8429540, 28793492, 70537376, 130418288, 186929600, 210477696, 186929600, 130418288, 70537376, 28793492, 8429540, 1593343, 147456, 1)1064175888

Every vector includes the empty face and the whole polytope. The table uses exact integers, is symmetric by self-duality, and satisfies Σfi = 4n − 2·3n−1 + 2.

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