Symmetry in the vanishing of Ext over Gorenstein rings

Abstract

We investigate symmetry in the vanishing of Ext for finitely generated modules over local Gorenstein rings. In particular, we define a class of local Gorenstein rings, which we call AB rings, and show that for finitely generated modules $M$ and $N$ over an AB ring $R$, $Ex{t}_R^i(M,N)=0$ for all $i>>0$ if and only if $Ex{t}_R^i(N,M)=0$ for all $i>>0$.

This paper appeared in 2003