Regular polyhedron a hemisphere, and vertices around a great circle. It is "regular" if the vertices are equally spaced. The hosohedron {2,"n"} is dual to the dihedron {"n",2}. Note that when "n" = 2, we obtain the polyhedron {2,2}, which is both a hosohedron and a dihedron. All of these have Euler characteristic 2. Regular polyhedron A regular polyhedron is a polyhedron whose symmetry group acts transitively on its flags. A regular polyhedron is highly symmetrical, being all of edge-transitive, vertex-transitive and face-transitive. In classical contexts, many different equivalent definitions are used; a common one is that faces are congruent regular polygons
Rectification (geometry) 2r{p,q...}. For polyhedra, a birectification creates a dual polyhedron. Higher degree rectifications can be constructed for higher dimensional polytopes. In general an n-rectification truncates "n-faces" to points. If an n-polytope is (n-1)-rectified, its facets are reduced to points and the polytope becomes its dual. There are different equivalent notations for each degree of rectification. These tables show the names by dimension and the two type of facets for each. Facets are edges, represented as {2}. Facets are regular polygons. Facets are regular or rectified polyhedra. Facets are regular or rectified 4-polytopes. Rectification (geometry) In Euclidean geometry, rectification or complete-truncation is