Non-commutative resolutions of quotient singularities

Abstract

In this paper we generalize standard results about non-commutative resolutions of quotient singularities for finite groups to arbitrary reductive groups. We show in particular that quotient singularities for reductive groups always have non-commutative resolutions in an appropriate sense. Moreover we exhibit a large class of such singularities which have (twisted) non-commutative crepant resolutions. We discuss a number of examples, both new and old, that can be treated using our methods. Notably we prove that twisted non-commutative crepant resolutions exist in previously unknown cases for determinantal varieties of symmetric and skew-symmetric matrices. In contrast to almost all prior results in this area our techniques are algebraic and do not depend on knowing a commutative resolution of the singularity.

Final version. Many corrections by the referee implemented

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• Discriminants and Quasi-symmetry
• A class of perverse schobers in Geometric Invariant Theory
• Semi-steady non-commutative crepant resolutions via regular dimer models
• Equivariant Tilting Modules, Pfaffian Varieties and Noncommutative Matrix Factorizations