English

Infinite reduced words and the Tits boundary of a Coxeter group

Group Theory 2014-09-19 v3 Combinatorics Geometric Topology Representation Theory

Abstract

Let (W,S) be a finite rank Coxeter system with W infinite. We prove that the limit weak order on the blocks of infinite reduced words of W is encoded by the topology of the Tits boundary of the Davis complex X of W. We consider many special cases, including W word hyperbolic, and X with isolated flats. We establish that when W is word hyperbolic, the limit weak order is the disjoint union of weak orders of finite Coxeter groups. We also establish, for each boundary point \xi, a natural order-preserving correspondence between infinite reduced words which "point towards" \xi, and elements of the reflection subgroup of W which fixes \xi.

Keywords

Cite

@article{arxiv.1301.0873,
  title  = {Infinite reduced words and the Tits boundary of a Coxeter group},
  author = {Thomas Lam and Anne Thomas},
  journal= {arXiv preprint arXiv:1301.0873},
  year   = {2014}
}

Comments

28 pages, 2 figures. Version 2: additional references in introduction. Version 3: results are unchanged but exposition has been substantially revised following referee's suggestions. To appear in Int. Math. Res. Not