The University of Michigan Combinatorics Seminar
Fall 2000
October 13, 4:10-5:00, 3866 East Hall



Bruhat Order for Two Flags and a Line

Peter Magyar

Michigan State University


Abstract

The classical Bruhat order describes the degeneration of a pair of flags from a more general to a less general relative position. The covers in this order (the minimal degenerations) correspond to reflections in the Weyl group. In this talk, we will describe the analogous situation for a pair of flags and a line. We classify the (finitely many) relative positions using quivers, and describe the covers, which involve cycles of length greater than 2. (Joint work with with J.Weyman and A.Zelevinsky.)