Conjugacy classes and straight elements in Coxeter groups

Abstract

Let W be a Coxeter group. In this paper, we establish that, up to going to some finite index normal subgroup W_0 of W, any two cyclically reduced expressions of conjugate elements of W_0 only differ by a sequence of braid relations and cyclic shifts. This thus provides a simple description of conjugacy classes in W_0. As a byproduct of our methods, we also obtain a characterisation of straight elements of W, namely of those elements w in W for which $\ell (w^n)=n\ell (w)$ for any integer n. In particular, we generalise previous characterisations of straight elements within the class of so-called cyclically fully commutative (CFC) elements, and we give a shorter and more transparent proof that Coxeter elements are straight.

12 pages, to appear in Journal of Algebra

Cited by in corpus (6)

• Cyclically reduced elements in Coxeter groups
• Decompositions of Kac-Moody groups
• Orthogonal forms of Kac--Moody groups are acylindrically hyperbolic
• Morphisms and order ideals of toric posets
• Toric heaps, cyclic reducibility, and conjugacy in Coxeter groups
• Structure of conjugacy classes in Coxeter groups