KING , Andrew D.

Consider an undirected graph $G$ and a subgraph $H$ of $G$, on the same vertex set. The {\it $q$-backbone chromatic number} $\BBC_q(G,H)$ is the minimum $k$ such that $G$ can be properly coloured with colours from $\{1, \dots, k\}$, and moreover for each edge of $H$, the colours of its ends differ by at least $q$. In this paper we focus on the...