Quasi-Gorensteinness of extended Rees algebras

Abstract

Let $R$ be a Noetherian local ring and $I$ an $R$-ideal. It is well-known that if the associated graded ring \gr_I(R) is Cohen-Macaulay (Gorenstein), then so is $R$, but the converse is not true in general. In this paper we investigate the Cohen-Macaulayness and Gorensteinness of the associated graded ring \gr_I(R) under the hypothesis of the extended Rees algebra $R[It,t^{-1}]$ is quasi-Gorenstein or the associated graded ring \gr_I(R) is a domain.Comment: to appear in Journal of Commutative Algebr