Cohen-Macaulayness of powers of edge ideals of edge-weighted graphs

TL;DR

This paper characterizes when powers of weighted edge ideals of certain graphs are Cohen-Macaulay, focusing on well-covered graphs, trees with perfect matchings, and specific induced subgraphs.

Contribution

It provides new characterizations of Cohen-Macaulayness for powers of weighted edge ideals in well-covered graphs, trees, and graphs with particular structures.

Findings

Cohen-Macaulayness of second powers of weighted edge ideals in well-covered graphs characterized.

Cohen-Macaulayness of all powers of weighted edge ideals in specific tree structures characterized.

Conditions for Cohen-Macaulayness in graphs with perfect matchings and particular induced subgraphs established.

Abstract

In this paper, we characterize the Cohen-Macaulayness of the second power $I(G_\omega)^2$ of the weighted edge ideal $I(G_\omega)$ when the underlying graph $G$ is a very well-covered graph. We also characterize the Cohen-Macaulayness of all ordinary powers of $I(G_\omega)^n$ when $G$ is a tree with a perfect matching consisting of pendant edges and the induced subgraph $G[V(G)\setminus S]$ of $G$ on $V(G)\setminus S$ is a star, where $S$ is the set of all leaf vertices, or if $G$ is a connected graph with a perfect matching consisting of pendant edges and the induced subgraph $G[V(G)\setminus S]$ of $G$ on $V(G)\setminus S$ is a complete graph and the weight function $\omega$ satisfies $\omega(e)=1$ for all $e\in E(G[V(G)\setminus S])$.