Small ditrigonary icosidodecahedral antiprism

The small ditrigonary icosidodecahedral antiprism or sidtidap, is a nonconvex uniform polychoron that consists of 2 small ditrigonary icosidodecahedra, 12 pentagrammic antiprisms, and 40 tetrahedra. Each vertex joins 1 small ditrigonary icosidodecahedron, 3 pentagrammic antiprisms, and 4 tetrahedra.

It can be obtained as a holosnub dodecahedral prism.

Vertex coordinates
The vertices of a small ditrigonary icosidodecahedral antiprism of edge length 1 are given by: along with all even permutations of the first three coordinates of:
 * $$\left(±\frac12,\,±\frac12,\,±\frac12,\,±\sqrt{\frac{\sqrt5-1}{8}}\right),$$
 * $$\left(±\frac{1+\sqrt5}{4},\,±\frac{\sqrt5-1}{4},\,0,\,±\sqrt{\frac{\sqrt5-1}{8}}\right).$$

Related polychora
The regiment of the small ditrigonary icosidodecahedral antiprism also includes the ditrigonary dodecadodecahedral antiprism and the great ditrigonary icosidodecahedral antiprism.

The small icosicosidodecahedral alterprism is a Stott expansion of this polychoron.