English

Multigraded linear series and recollement

Algebraic Geometry 2017-10-12 v4

Abstract

Given a scheme YY equipped with a collection of globally generated vector bundles E1,,EnE_1, \dots, E_n, we study the universal morphism from YY to a fine moduli space M(E)\mathcal{M}(E) of cyclic modules over the endomorphism algebra of E:=OYE1EnE:=\mathcal{O}_Y\oplus E_1\oplus\cdots \oplus E_n. This generalises the classical morphism to the linear series of a basepoint-free line bundle on a scheme. We describe the image of the morphism and present necessary and sufficient conditions for surjectivity in terms of a recollement of a module category. When the morphism is surjective, this gives a fine moduli space interpretation of the image, and as an application we show that for a small, finite subgroup GGL(2,k)G\subset \text{GL}(2,k), every sub-minimal partial resolution of Ak2/G\mathbb{A}^2_k/G is isomorphic to a fine moduli space M(EC)\mathcal{M}(E_C) where ECE_C is a summand of the bundle EE defining the reconstruction algebra. We also consider applications to Gorenstein affine threefolds, where Reid's recipe sheds some light on the classes of algebra from which one can reconstruct a given crepant resolution.

Keywords

Cite

@article{arxiv.1701.01679,
  title  = {Multigraded linear series and recollement},
  author = {Alastair Craw and Yukari Ito and Joseph Karmazyn},
  journal= {arXiv preprint arXiv:1701.01679},
  year   = {2017}
}

Comments

30 pages, previous upload was not quite the final version as claimed; this version to appear in Mathematische Zeitschrift

R2 v1 2026-06-22T17:43:03.897Z