Gapfree graphs and powers of edge ideals with linear quotients

Abstract

Let $I(G)$ be the edge ideal of a gapfree graph $G$. An open conjecture of Nevo and Peeva states that $I(G{)}^q$ has linear resolution for $q\gg 0$. We present a promising approach to this challenging conjecture by investigating the stronger property of linear quotients. Specifically, we make the conjecture that if $I(G{)}^q$ has linear quotients for some integer $q\ge 1$, then $I(G{)}^s$ has linear quotients for all $s\ge q$. We give a partial solution to this conjecture, and identify conditions under which only finitely many powers need to be checked. It is known that if $G$ does not contain a cricket, a diamond, or a $C_4$, then $I(G{)}^q$ has linear resolution for $q\ge 2$. We construct a family of gapfree graphs $G$ containing cricket, diamond, $C_4$ together with $C_5$ as induced subgraphs of $G$ for which $I(G{)}^q$ has linear quotients for $q\ge 2$.

arXiv comment27 pages, 6 figures