Transactions on Combinatorics (Jun 2013)
On the complexity of the colorful directed paths in vertex coloring of digraphs
Abstract
The colorful paths and rainbow paths have been considered by severalauthors.A colorful directed path in a digraph $G$ is a directed path with $chi(G)$ vertices whose colors are different. A $v$-colorful directed path is such a directed path, starting from $v$. We prove that for a given $3$-regular triangle-free digraph $G$ determining whether there is a proper $chi(G)$-coloring of $G$such that for every $v in V (G)$, there exists a $v$-colorful directed path is $ mathbf{NP} $-complete.