Combinatorics Seminar: "Lexicographic shellability"

Speaker: Tiansi Li, Washington University in Saint Louis

Abstract: Lexicographic shellability is defined and studied by Bjorner and Wachs as a way of computing the homology groups of shellable posets by either labeling edges (for EL-shellable posets) or labeling pairs of edges and maximal chains (for CL-shellable posets) in the Hasse diagrams. In this talk, I will give relevant definitions with examples. I will show that certain operations on posets, such as taking Cartesian product and rank-selected subposets, preserve EL-shellability and CL-shellability. And I will introduce some open problems in this field.

Host: Martha Precup