Bounding invariants of fat points using a coding theory construction

Abstract

Let $Z\subseteq {\mathbb{P}}^n$ be a fat point scheme, and let $d\left(Z\right)$ be the minimum distance of the linear code constructed from $Z$. We show that $d\left(Z\right)$ imposes constraints (i.e., upper bounds) on some specific shifts in the graded minimal free resolution of $I_Z$, the defining ideal of $Z$. We investigate this relation in the case that the support of $Z$ is a complete intersection; when $Z$ is reduced and a complete intersection we give lower bounds for $d\left(Z\right)$ that improve upon known bounds.