English

On Tor-vanishing of local rings

Commutative Algebra 2025-06-30 v1

Abstract

Let RR be a local ring with residue field kk and MM, NN be finitely generated modules over RR. It is well known that ToriR(M,N)=0Tor^R_i(M, N) = 0 for i0i \gg 0 if pdR(M)<pd_R(M) < \infty or pdR(N)<pd_R(N) < \infty. The ring RR is said to satisfy the Tor-vanishing property if the converse holds, that is, ToriR(M,N)=0Tor^R_i(M, N) = 0 for i0i \gg 0 implies pdR(M)<pd_R(M) < \infty or pdR(N)<pd_R(N) < \infty. Interest in the Tor-vanishing property stems from the fact that Cohen-Macaulay local rings satisfying this property also satisfy the Auslander-Reiten conjecture. In this article, we study a variant of this property. If RR is a generalized Golod ring, we prove that ToriR(M,N)=0Tor^R_i(M, N) = 0 for i0i \gg 0 implies {curvRM,curvRN}{0,1}\{curv_R M, curv_R N \} \cap \{0, 1\} \neq \emptyset. A key intermediate step in our proof is to show that curvRM{0,1,curvRk}curv_R M \in \{0, 1, curv_R k\} for any module MM over a generalized Golod ring RR. As an application, we prove that generic Gorenstein local rings, non-trivial connected sums of generalized Golod-Gorenstein rings satisfy the Tor-vanishing property and consequently the Auslander-Reiten conjecture. Our method suggests a uniform approach and recovers many old results on the Tor-vanishing property.

Keywords

Cite

@article{arxiv.2506.21764,
  title  = {On Tor-vanishing of local rings},
  author = {Shrikant Shekhar and Anjan Gupta},
  journal= {arXiv preprint arXiv:2506.21764},
  year   = {2025}
}

Comments

This work is part of the first author's Ph.D. dissertation