A note on the Gallai-Roy-Vitaver Theorem

Gerard J. Chang, Li Da Tong, Jing Ho Yan, Hong Gwa Yeh

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2 Scopus citations


The well-known theorem by Gallai-Roy-Vitaver says that every digraph G has a directed path with at least χ(G) vertices; hence this holds also for graphs. Li strengthened the digraph result by showing that the directed path can be constrained to start from any vertex that can reach all others. For a graph G given a proper χ(G)-coloring, he proved that the path can be required to start at any vertex and visit vertices of all colors. We give a shorter proof of this. He conjectured that the same holds for digraphs; we provide a strongly connected counterexample. We also give another extension of the Gallai-Roy-Vitaver Theorem on graphs.

Original languageEnglish
Pages (from-to)441-444
Number of pages4
JournalDiscrete Mathematics
Issue number1-2
StatePublished - 28 Sep 2002


  • Chromatic number
  • Coloring
  • K-Coloring
  • Path
  • Tournament


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