2012/05/03 by Jean‐Luc Fouquet, Fouquet, Jean-Luc, Jean-Marie Vanherpe +1 · 1 citation
Computer Science · Mathematics · #Advanced Graph Theory Research #Discrete Mathematics (cs.DM) #FOS: Computer and information sciences #Graph Labeling and Dimension Problems #Limits and Structures in Graph Theory
paper · pdf · doi:10.48550/arxiv.1205.0731
openalex publication_date 2012/05/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In 1998, Reed conjectured that for any graph G, χ(G) ≤ \lceil (ω(G) + Δ(G)+1)/(2)\rceil, where χ(G), ω(G), and Δ(G) respectively denote the chromatic number, the clique number and the maximum degree of G. In this paper, we study this conjecture for some expansions of graphs, that is graphs obtained with the well known operation composition of graphs. We prove that Reed's Conjecture holds for expansions of bipartite graphs, for expansions of odd holes where the minimum chromatic number of the components is even, when some component of the expansion has chromatic number 1 or when a component induces a bipartite graph. Moreover, Reed's Conjecture holds if all components have the same chromatic number, if the components have chromatic number at most 4 and when the odd hole has length 5. Finally, when G is an odd hole expansion, we prove χ(G)≤\lceil(ω(G)+Δ(G)+1)/(2)\rceil+1.