English

A McKay correspondence for reflection groups

Algebraic Geometry 2020-03-18 v3 Commutative Algebra Representation Theory

Abstract

We construct a noncommutative desingularization of the discriminant of a finite reflection group GG as a quotient of the skew group ring A=SGA=S*G. If GG is generated by order two reflections, then this quotient identifies with the endomorphism ring of the reflection arrangement A(G)\mathcal{A}(G) viewed as a module over the coordinate ring SG/(Δ)S^G/(\Delta) of the discriminant of GG. This yields, in particular, a correspondence between the nontrivial irreducible representations of GG to certain maximal Cohen--Macaulay modules over the coordinate ring SG/(Δ)S^G/(\Delta). These maximal Cohen--Macaulay modules are precisely the nonisomorphic direct summands of the coordinate ring of the reflection arrangement A(G)\mathcal{A} (G) viewed as a module over SG/(Δ)S^G/(\Delta). We identify some of the corresponding matrix factorizations, namely the so-called logarithmic (co-)residues of the discriminant.

Keywords

Cite

@article{arxiv.1709.04218,
  title  = {A McKay correspondence for reflection groups},
  author = {Ragnar-Olaf Buchweitz and Eleonore Faber and Colin Ingalls},
  journal= {arXiv preprint arXiv:1709.04218},
  year   = {2020}
}

Comments

Major revision. Final version, to appear in Duke Math. Journal. 52pages

R2 v1 2026-06-22T21:41:32.329Z