The Auslander-Reiten Conjecture, Finite $C$-Injective Dimension of $\operatorname{Hom}$, and vanishing of $\operatorname{Ext}$
Victor D. Mendoza-Rubio, Victor H. Jorge-Pérez
TL;DR
This work extends the Auslander–Reiten conjecture framework by linking Ext vanishing, finite injective dimension of Hom, and finite $C$-injective dimension for semidualizing $C$. Building on Ghosh–Takahashi, it proves that under suitable Ext-vanishing and finiteness hypotheses, modules $M$ must be free and related modules $N$ have finite injective dimensions, with sharpened conclusions when $R$ is Cohen–Macaulay or Gorenstein. It then develops a $C$-version of these results, showing that finite $ ext{I}_C$-id of $ ext{Hom}$ transfers through $C$-tensor products and Ext vanishing, yielding AR conjecture in broader contexts and new canonical-module criteria. The paper further characterizes when a semidualizing module $C$ is canonical via finite $ ext{I}_C$-id conditions on Hom, including implications for CM and Gorenstein structures and extending known results in the literature to the $C$-injective framework.
Abstract
Let $R$ be a Noetherian local ring, and let $C$ be a semidualizing $R$-module. In this paper, we present some results concerning the vanishing of $\operatorname{Ext}$ and finite injective dimension of $\operatorname{Hom}$. Additionally, we extend these results in terms of finite $C$-injective dimension of $\operatorname{Hom}$. We also investigate the consequences of some of these extensions in the case where $R$ is Cohen-Macaulay and $C$ is a canonical module for $R.$ Furthermore, we provide positive answers to the Auslander-Reiten conjecture for finitely generated $R$-modules $M$ such that $\mathcal{I}_C\operatorname{-id}_R(\operatorname{Hom}_R(M,R))<\infty$ or $M \in \mathcal{A}_C(R)$ with $\mathcal{I}_C \operatorname{-id}_R(\operatorname{Hom}_R(M,M))<\infty$. Moreover, we derive a number of criteria for a semidualizing $R$-module $C$ to be a canonical module for $R$ in terms of the vanishing of $\operatorname{Ext}$ and the finite $C$-injective dimension of $\operatorname{Hom}$.
