English

Canonical reduced expression in affine Coxeter groups of type $\tilde{A}_n$, $\tilde{B}_n$, $\tilde{D}_n$

Representation Theory 2025-11-04 v1 Group Theory

Abstract

We classify the elements of W(A~n)W(\tilde{A}_n) by giving a canonical reduced expression for each, using basic tools among which affine length. We give some direct consequences for such a canonical form: a description of left multiplication by a simple reflection, a study of the right descent set, and a proof that the affine length is preserved along the tower of affine Coxeter groups of type A~\tilde A, which implies in particular that the corresponding tower of affine Hecke algebras is a faithful tower regardless of the ground ring. We give a similar canonical reduced expression for the elements of W(B~n)W(\tilde{B}_n) and W(D~n)W(\tilde{D}_n).

Keywords

Cite

@article{arxiv.2511.01702,
  title  = {Canonical reduced expression in affine Coxeter groups of type $\tilde{A}_n$, $\tilde{B}_n$, $\tilde{D}_n$},
  author = {Sadek Al Harbat},
  journal= {arXiv preprint arXiv:2511.01702},
  year   = {2025}
}