The dual Hilbert-Samuel function of a Maximal Cohen-Macaulay module

Abstract

Let $R$ be a Cohen-Macaulay local ring with a canonical module ${\omega }_R$. Let $I$ be an $\m$-primary ideal of $R$ and $M$, a maximal Cohen-Macaulay $R$-module. We call the function $n\longmapsto \ell (\Hom_R(M,{ω_R}/{I^{n+1} ω_R}))$ the dual Hilbert-Samuel function of $M$ with respect to $I$. By a result of Theodorescu this function is a polynomial function. We study its first two normalized coefficients.