English

$k$-colored kernels in semicomplete multipartite digraphs

Combinatorics 2012-02-20 v1

Abstract

An mm-colored digraph DD has kk-colored kernel if there exists a subset KK of its vertices such that for every vertex vKv\notin K there exists an at most kk-colored directed path from vv to a vertex of KK and for every % u,v\in K there does not exist an at most kk-colored directed path between them. In this paper we prove that an mm-colored semicomplete rr-partite digraph DD has a kk-colored kernel provided that r3r\geq 3 and {enumerate} [(i)] k4,k\geq 4, [(ii)] k=3k=3 and every C4\overrightarrow{C}_{4} contained in DD is at most 2-colored and, either every C5\overrightarrow{C}_{5} contained in DD is at most 3-colored or every C3C3\overrightarrow{C}_{3}\uparrow \overrightarrow{C}_{3} contained in DD is at most 2-colored, [(iii)] k=2k=2 and every C3\overrightarrow{C}_{3} and C\overrightarrow{C}%_{4} contained in DD is monochromatic. {enumerate} If DD is an mm-colored semicomplete bipartite digraph and k=2k=2 (resp. k=3k=3 ) and every C4C4\overrightarrow{C}_{4}\upuparrows \overrightarrow{C}_{4} contained in DD is at most 2-colored (resp. 3-colored), then DD has a % 2-colored (resp. 3-colored) kernel. Using these and previous results, we obtain conditions for the existence of kk-colored kernels in mm-colored semicomplete rr-partite digraphs for every k2k\geq 2 and r2r\geq 2.

Keywords

Cite

@article{arxiv.1202.4017,
  title  = {$k$-colored kernels in semicomplete multipartite digraphs},
  author = {Hortensia Galeana-Sánchez and Bernardo Llano and Juan José Montellano-Ballesteros},
  journal= {arXiv preprint arXiv:1202.4017},
  year   = {2012}
}
R2 v1 2026-06-21T20:21:21.953Z