= 2r2r{p,q,r,s} and has Coxeter diagram . The general operator for expansion of a regular n-polytope is t0,n-1{p,q,r,...}. New regular facets are added at each vertex, and new prismatic polytopes are added at each divided edge, face, ... ridge, etc. See also Conway polyhedron notation Notes References Coxeter, H. S. M., Regular Polytopes. 3rd edition, Dover, (1973) . Norman Johnson Uniform Polytopes, Manuscript (1991) N.W. Johnson: The Theory of Uniform Polytopes and Honeycombs, Ph.D. Dissertation, University of Toronto, 1966 Euclidean geometry Polytopes