Hoffman-London graphs: When paths minimize $H$-colorings among trees

David Galvin, Phillip Marmorino, Emily McMillon +2

Given a graph $G$ and a target graph $H$, an $H$-coloring of $G$ is an adjacency-preserving vertex map from $G$ to $H$. The number of $H$-colorings of $G$, $\mathrm{hom}(G,H)$, has been st…