English

Atom spectra of graded rings and sheafification in toric geometry

Algebraic Geometry 2020-10-15 v1 Category Theory

Abstract

We prove that the atom spectrum, which is a topological space associated to an arbitrary abelian category introduced by Kanda, of the category of finitely presented graded modules over a graded ring RR is given as a union of the homogeneous spectrum of RR with some additional points, which we call non-standard points. This description of the atom spectrum helps in understanding the sheafification process in toric geometry: if SS is the Cox ring of a normal toric variety XX without torus factors, then a finitely presented graded SS-module sheafifies to zero if and only if its atom support consists only of points in the atom spectrum of SS which either lie in the vanishing locus of the irrelevant ideal of XX or are non-standard.

Keywords

Cite

@article{arxiv.1808.08792,
  title  = {Atom spectra of graded rings and sheafification in toric geometry},
  author = {Sebastian Posur},
  journal= {arXiv preprint arXiv:1808.08792},
  year   = {2020}
}