On Kalai's conjectures concerning centrally symmetric polytopes

Abstract

In 1989, Kalai stated three conjectures A, B, C of increasing strength concerning face numbers of centrally symmetric convex polytopes. The weakest conjecture, A, became known as the "3 d -conjecture." It is well known that the three conjectures hold in dimensions d3. We show that in dimension 4 only conjectures A and B are valid, while conjecture C fails. Furthermore, we show that both conjectures B and C fail in all dimensions d5. © 2008 Springer Science+Business Media, LLC.