Oriented vertex and arc colorings of outerplanar graphs

A homomorphism from an oriented graph G to an oriented graph H is an arc-preserving mapping from V (G) to V (H), that is (x)(y) is an arc in H whenever xy is an arc in G. The oriented chromatic number of G is the minimum order of an oriented graph H such that G has a homomorphism to H. The oriented chromatic index of G is the minimum order of an oriented graph H such that the line-digraph of G has a homomorphism to H. In this paper, we determine for every k 3 the oriented chromatic number and the oriented chromatic index of the class of oriented outerplanar graphs with girth at least k.

• Type: Journal
• Year: 2006
• Where: IPL
• Authors: Alexandre Pinlou, Eric Sopena
• Keywords: Homomorphism, IPL 2006, Oriented Chromatic Number, Oriented Graph