$H$-kernels in $H$-colored digraphs without $(\xi_{1}, \xi, \xi_{2})$-$H$-subdivisions of $\overrightarrow{C_{3}}$
Abstract
Let be a digraph possibly with loops and a digraph without loops with a coloring of its arcs ( is said to be an -colored digraph). A directed path in is said to be an -path if and only if the consecutive colors encountered on form a directed walk in . A subset of vertices of is said to be an -kernel if (1) for every pair of different vertices in there is no -path between them and (2) for every vertex in V() there exists an -path in from to . Under this definition an -kernel is a kernel whenever . The color-class digraph () of is the digraph whose vertices are the colors represented in the arcs of and (,) (()) if and only if there exist two arcs, namely (,) and (,) in , such that (,) has color and (,) has color . Since not every -colored digraph has an -kernel and , the natural question is: what structural properties of , with respect to the -coloring, imply that has an -kernel? In this paper we investigate the problem of the existence of an -kernel by means of a partition of and a partition \{, \} of . We establish conditions on the directed cycles and the directed paths of the digraph , with respect to the partition \{, \}. In particular we pay attention to some subestructures produced by the partitions and \{, \}, namely --subdivisions of and --subdivisions of . We give some examples which show that each hypothesis in the main result is tight.
Keywords
Cite
@article{arxiv.2006.03691,
title = {$H$-kernels in $H$-colored digraphs without $(\xi_{1}, \xi, \xi_{2})$-$H$-subdivisions of $\overrightarrow{C_{3}}$},
author = {Felipe Hernández-Lorenzana and Rocío Sánchez-López},
journal= {arXiv preprint arXiv:2006.03691},
year = {2020}
}
Comments
15 pages, 5 figures