 The gaps between the separated vertices become {r,q} cells.The vertex figure for a regular 4-polytope {p,q,r} is an "q"-gonal antiprism (called an "antipodium" if "p" and "r" are different).For regular 4-polytopes/honeycombs, this operation is also called expansion by Alicia Boole Stott, as imagined by moving the cells of the regular form away from the center, and filling in new faces in the gaps for each opened vertex and edge.