Packing coloring of some undirected and oriented coronae graphs

Abstract

The packing chromatic number $\pcn(G)$ of a graph $G$ is the smallest integer $k$ such that its set of vertices $V(G)$ can be partitioned into $k$ disjoint subsets $V\_1$, \ldots, $V\_k$, in such a way that every two distinct vertices in $V\_i$ are at distance greater than $i$ in $G$ for every $i$, $1\le i\le k$. For a given integer $p\ge 1$, the generalized corona $G\odot pK\_1$ of a graph $G$ is the graph obtained from $G$ by adding $p$ degree-one neighbors to every vertex of $G$. In this paper, we determine the packing chromatic number of generalized coronae of paths and cycles. Moreover, by considering digraphs and the (weak) directed distance between vertices, we get a natural extension of the notion of packing coloring to digraphs. We then determine the packing chromatic number of orientations of generalized coronae of paths and cycles.

Cited by in corpus (1)

• Packing chromatic number under local changes in a graph