English

Cohomological support varieties for monomial ideals

Commutative Algebra 2026-05-29 v1 Combinatorics

Abstract

Let RR be a local or positively graded ring with a regular presentation RQ/IR \cong Q/I where II is a monomial ideal generated by nn elements on a regular sequence. In Briggs-Grifo-Pollitz (2025), the authors classify the cohomological support varieties VR(R)\mathcal{V}_R(R) for n5n \leqslant 5. In this paper we extend their results to classify the varieties that can occur as VR(R)\mathcal{V}_R(R) for n=6n=6. Moreover, we provide two families of rings, one realizing cohomological support varieties of unbounded codimension, the other realizing an unbounded number of components. Finally, we answer a question of Gintz (2026) about the varieties that occur as VR(R)\mathcal{V}_R(R) where II is given by the edge ideal of a cycle.

Keywords

Cite

@article{arxiv.2605.29103,
  title  = {Cohomological support varieties for monomial ideals},
  author = {Kara Fagerstrom and Julianne Faur and Benjamin Katz and Kesavan Mohana Sundaram and Stephen Stern and Ryan Watson},
  journal= {arXiv preprint arXiv:2605.29103},
  year   = {2026}
}

Comments

32 pages. Comments welcome