Regular Sequences On Squares Of Monomial Ideals

Abstract

We use initially regular sequences that consist of linear sums to explore the depth of $R/I^2$, when $I$ is a monomial ideal in a polynomial ring $R$. We give conditions under which these linear sums form regular or initially regular sequences on $R/I^2$. We then obtain a criterion for when $\depth R/I^2>1$ and a lower bound on $\depth R/I^2$.

Revised version, to appear in Sao Paolo Journal of Math in special volume in honor of Rafael Villarreal