A Lower Bound For Depths of Powers of Edge Ideals

Abstract

Let $G$ be a graph and let $I$ be the edge ideal of $G$. Our main results in this article provide lower bounds for the depth of the first three powers of $I$ in terms of the diameter of $G$. More precisely, we show that \depth R/I^t \geq \left\lceil{\frac{d-4t+5}{3}} \right\rceil +p-1, where $d$ is the diameter of $G$, $p$ is the number of connected components of $G$ and $1 \leq t \leq 3$. For general powers of edge ideals we showComment: 21 pages, to appear in Journal of Algebraic Combinatoric