The Number of Vertices in a Cubical Complex

Steve Klee
Department of Mathematics, University of Washington

Abstract: A cubical complex is a geometric object that can be decomposed into hypercubes of various dimensions. The simplest example of a d-dimensional cubical complex is the boundary of a (d+1)-dimensional cube, which gives a cubical decomposition of a d-dimensional sphere. In particular, the boundary of a (d+1)-dimensional cube has 2d+1 vertices. In this talk, we will give a precise combinatorial definition of cubical complexes and prove that any cubical decomposition of a d-sphere requires at least 2d+1 vertices.