Combinatorica

, Volume 22, Issue 1, pp 35–46 | Cite as

Homomorphisms of Products of Graphs into Graphs Without Four Cycles

  • Christian Delhommé
  • Norbert Sauer
Original Paper

Given two graphs A and G, we write \(\) if there is a homomorphism of A to G and \(\) if there is no such homomorphism. The graph G is \(\)-free if, whenever both a and c are adjacent to b and d, then a = c or b = d. We will prove that if A and B are connected graphs, each containing a triangle and if G is a \(\)-free graph with \(\) and \(\), then \(\) (here "\(\)" denotes the categorical product).

AMS Subject Classification (2000) Classes:  05C15 

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Copyright information

© János Bolyai Mathematical Society, 2002

Authors and Affiliations

  • Christian Delhommé
    • 1
  • Norbert Sauer
    • 2
  1. 1.University of Calgary, Department of Mathematics and Statistics; 2500 University Dr., N. W. Calgary, Alberta, T2N 1N4 Canada; E-mail: nsauer@math.ucalgary.caCA
  2. 2.E.R.M.I.T. Département de Mathématiques et d'Informatique, Université de La Réunion; 15, avenue René Cassin, BP 71551 97715 Saint-Denis Messag. Cedex 9, FRANCE; E-mail: delhomme@univ-reunion.frFR

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