Acronym | n/2-ap |
Name | n/2 antiprism |
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Circumradius | sqrt[(3-2 cos(2π/n))/(8-8 cos(2π/n))] |
Vertex figure |
[33,n/2] (n odd) 2[33,n/2] (n even) |
General of army |
if n odd: use a (stretched) n-p for its general if n even: (n:2)-ap |
Colonel of regiment | (is itself locally convex) |
Especially | trirp (n=3) stap (n=5) |
Face vector | 2n, 4n, 2n+2 |
Confer | n-ap n/d-ap |
External links |
n=3 (trirp) would result in the retrograde triangular antiprism with height of zero, i.e. all faces would coincide. (But consider xo3/2ox&#q for a non-degenerate, taller, non-uniform variant thereof.)
For n even this looks like a double cover of a (n:2)-antiprism (with winding number 1).
Incidence matrix according to Dynkin symbol
s2sn/2s (n>3) demi( . . . ) | 2n | 1 1 2 | 1 3 -----------------+----+--------+----- s2s . ♦ 2 | n * * | 0 2 s . s2*a ♦ 2 | * n * | 0 2 sefa( . sn/2s ) | 2 | * * 2n | 1 1 -----------------+----+--------+----- . sn/2s ♦ n | 0 0 n | 2 * sefa( s2sn/2s ) | 3 | 1 1 1 | * 2n
β2βno (n>2, odd) both( . . . ) | 2n | 1 1 2 | 1 3 ----------------+----+--------+----- s2s . (r) ♦ 2 | n * * | 0 2 s2s . (l) ♦ 2 | * n * | 0 2 sefa( . βno ) | 2 | * * 2n | 1 1 ----------------+----+--------+----- . βno ) ♦ n | 0 0 n | 2 * sefa( β2βno ) | 3 | 1 1 1 | * 2n
or both( . . . ) | 2n | 2 2 | 1 3 --------------+----+-------+----- both( s2s . ) ♦ 2 | 2n * | 0 2 sefa( . βno ) | 2 | * 2n | 1 1 --------------+----+-------+----- . βno ♦ n | 0 n | 2 * sefa( β2βno ) | 3 | 2 1 | * 2n
xon/2ox&#x (n>3) → height = sqrt[(1+2*cos(2pi/n))/(2+2*cos(2pi/n))]
({n/2} || dual {n/2})
o.n/2o. | n * | 2 2 0 | 1 2 1 0
.on/2.o | * n | 0 2 2 | 0 1 2 1
-----------+-----+--------+--------
x. .. | 2 0 | n * * | 1 1 0 0
oon/2oo&#x | 1 1 | * 2n * | 0 1 1 0
.. .x | 0 2 | * * n | 0 0 1 1
-----------+-----+--------+--------
x.n/2o. | n 0 | n 0 0 | 1 * * *
xo ..&#x | 2 1 | 1 2 0 | * n * *
.. ox&#x | 1 2 | 0 2 1 | * * n *
.on/2.x | 0 n | 0 0 n | * * * 1
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