English

Comparing the Kirwan and noncommutative resolutions of quotient varieties

Algebraic Geometry 2026-02-18 v2 Rings and Algebras Representation Theory

Abstract

Let a reductive group GG act on a smooth variety XX such that a good quotient X/ ⁣ ⁣/GX{/\!\!/}G exists. We show that the derived category of a noncommutative crepant resolution (NCCR) of X/ ⁣ ⁣/GX{/\!\!/} G, obtained from a GG-equivariant vector bundle on XX, can be embedded in the derived category of the (canonical, stacky) Kirwan resolution of X/ ⁣ ⁣/GX{/\!\!/} G. In fact the embedding can be completed to a semi-orthogonal decomposition in which the other parts are all derived categories of Azumaya algebras over smooth Deligne-Mumford stacks.

Keywords

Cite

@article{arxiv.1912.01689,
  title  = {Comparing the Kirwan and noncommutative resolutions of quotient varieties},
  author = {Špela Špenko and Michel Van den Bergh},
  journal= {arXiv preprint arXiv:1912.01689},
  year   = {2026}
}

Comments

40 pages. v2: Correct ERC funding acknowledgement