V-numbers of symbolic powers of cover ideals of graphs

Abstract

Let $G$ be a simple graph with cover ideal $J(G)$ in a polynomial ring $S$ with $|V(G)|$ variables. We prove that the local $v$-number of the symbolic powers $J(G{)}^{(t)}$ is linear for all $t\ge 1$ when $G$ is bipartite, and quasi-linear with period two for all $t\ge 2$ when $G$ is non-bipartite. Furthermore, we provide explicit formulas for these invariants in terms of the combinatorial data of $G$.