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A counterexample for Hilton-Johnson’s conjecture on list-coloring of graphs. (English) Zbl 0914.05026

A. J. W. Hilton and P. D. Johnson conjectured that the Hall index of every graph is at most 3. The authors of the present paper show that for every integer \(k\) there exists a graph whose Hall index is greater than \(k\).

MSC:

05C15 Coloring of graphs and hypergraphs
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