Algebra and Combinatorics Seminar

Date: October 26, 2018

Time: 3:00PM - 4:00PM

Location: BLOC 628

Speaker: Anastasia Chavez, University of California, Davis

Title: Dual Equivalence Graphs and CAT(0) Combinatorics

Abstract: In this talk we will explore the combinatorial structure of dual equivalence graphs G_lambda. The vertices are Standard Young tableaux of fixed shape lambda that allows us to further understand the combinatorial structure of G_lambda, and the edges are given by dual Knuth equivalences. The graph G_lambda is the 1-skeleton of a cubical complex C_lambda. One can ask whether the cubical complex is CAT(0); this is a desirable metric property that allows us to describe the combinatorial structure of G_lambda very explicitly. We will discuss the CAT(0) characterization of Ardila--Owen--Sullivant. It is constructive and provides an algorithm for determining when a cubical complex is CAT(0). Using their characterization, we prove that C_lambda is CAT(0) if and only if lambda is a hook. This is joint work with John Guo.