English

Hecke algebras of classical type and their representation type

Quantum Algebra 2007-05-23 v3 Representation Theory

Abstract

Let WW be a finite Weyl group of classical type which may not be irreducible, FF an algebraically closed field, qq an invertible element of FF. We denote by HW(q)\mathcal H_W(q) the associated Hecke algebra. If q=1q=1 then it is FWFW and we know the representation type. Thus, we assume that q1q\ne 1. Let PW(x)P_W(x) be the Poincare polynomial of WW. It is well-known that HW(q)\mathcal H_W(q) is semisimple if and only if xqx-q does not divide PW(x)P_W(x). We show that the similar results hold for finiteness, tameness and wildness. In other words, the Poincare polynomial governs the representation type of HW(q)\mathcal H_W(q) completely. Note that the finiteness result was already given in the author's previous papers, some of which were written with Andrew Mathas. The proof uses the Fock space theory, which was developed for proving the LLT conjecture (see AMS Univ. Lec. Ser. 26), the Specht module theory, which was developed by Dipper, James and Murphy in this case, and results from the theory of finite dimensional algebras.

Keywords

Cite

@article{arxiv.math/0302136,
  title  = {Hecke algebras of classical type and their representation type},
  author = {Susumu Ariki},
  journal= {arXiv preprint arXiv:math/0302136},
  year   = {2007}
}

Comments

57 pages, Appendix (errata to my book) expanded, (case 5a) corrected

R2 v1 2026-07-22T16:51:53.717Z