A convex 3-complex not simplicially isomorphic to a strictly convex complex

Abstract

A set X in euclidean space is convex if the line segment joining any two points of X is in X. If X is convex, every boundary point is on an (n − 1)-plane which contains X in one of its two closed half-spaces. Such a plane is called a support plane for X. A simplicial complex K in is called strictly convex if |K| (the underlying space of K) is convex and if, for every simplex σ in ∂K (the boundary of K) there is a support plane for |K| whose intersection with |K| is precisely σ In this case |K| is often called a simplicial polytope.