Vanishing of (co)homology of Burch and related submodules

Abstract

We introduce the notion of Burch submodules and weakly $\mathfrak{m}$-full submodules of modules over local rings and study their properties. One of our main results shows that Burch submodules satisfy 2-Tor rigid and test property. We also show that over a local ring $(R,\mathfrak{m})$ a submodule $M$ of a finitely generated $R$-module $X$, such that either $M=\mathfrak{m}X$ or $M(\subseteq \mathfrak{m}X$) is weakly $\mathfrak{m}$-full in $X$, is 1-Tor rigid and a test module provided that $X$ is faithful (and $X/M$ has finite length when $M$ is weakly $\mathfrak{m}$-full). As an application, we give a new class of rings such that a conjecture of Huneke and Wiegand is affirmative over them.

Revised version; 31 pages. Key word Ulrich module and some new results added. Accepted at Illinois Journal of Mathematics

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