English

Cohomological support varieties under local homomorphisms

Commutative Algebra 2025-06-13 v1

Abstract

Given a bounded complex of finitely generated modules MM over a commutative noetherian local ring RR, one assigns to it a variety, VR(M)\mathcal V_R(M), called the cohomological support variety of MM over RR. The variety VR(M)\mathcal V_R(M) holds important homological information about the complex and the ring. In this paper, we study the behavior of cohomological support varieties under restriction of scalars along local maps. In the case where the rings involved are complete intersections and the map is a surjective complete intersection, this recovers a theorem of Bergh and Jorgensen. Additionally, we show that if RSR\to S is a local map of finite flat dimension, then the dimension of VR(R)\mathcal V_R(R) is less than or equal to that of VS(S)\mathcal V_S(S). This allows us to recover Avramov's result that the complete intersection property is preserved under localization.

Keywords

Cite

@article{arxiv.2506.10757,
  title  = {Cohomological support varieties under local homomorphisms},
  author = {Ryan Watson},
  journal= {arXiv preprint arXiv:2506.10757},
  year   = {2025}
}

Comments

18 pages

R2 v1 2026-07-01T03:13:32.946Z