Combinatorics Seminar: Coherence of cellular strings of zonotopes

Seminar | October 1 | 12-1 p.m. | 939 Evans Hall

 Thomas McConville, MSRI

 Department of Mathematics

A cellular string of a polytope is a sequence of faces of the polytope that are stacked on top of each other in a particular direction. The collection of cellular strings, ordered by refinement, forms a poset that is homotopy equivalent to a sphere. Among the set of strings, the subposet of coherent ones is homeomorphic to a sphere. In this talk, I will give an oriented matroid characterization of zonotopes whose poset of cellular strings is a sphere, i.e. for which all strings are coherent. This is based on joint work with Rob Edman, Pakawut Jiradilok, and Gaku Liu.