Boolean Complexes of Involutions

Abstract

Let (W, S) be a Coxeter system. We introduce the boolean complex of involutions of W which is an analogue of the boolean complex of W studied by Ragnarsson and Tenner. By applying discrete Morse theory, we determine the homotopy type of the boolean complex of involutions for a large class of (W, S), including all finite Coxeter groups, finding that the homotopy type is that of a wedge of spheres of dimension $$\vert S\vert -1$$ | S | - 1 . In addition, we find simple recurrence formulas for the number of spheres in the wedge.