Even Pairs in Bull-reducible Graphs

  • Celina M. H. de Figueiredo
  • Frédéric Maffray
  • Claudia Regina Villela Maciel
Part of the Trends in Mathematics book series (TM)


A bull is a graph with five vertices a, b, c, d, e and five edges ab, bc, cd, be, ce. A graph G is bull-reducible if no vertex of G lies in two bulls. An even pair is a pair of vertices such that every chordless path joining them has even length. We prove that for every bull-reducible Berge graph G with at least two vertices, either G or its complementary graph \( \bar G \) has an even pair.


Induction Hypothesis Bipartite Graph Pairwise Disjoint Adjacent Vertex Perfect Graph 
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Copyright information

© Birkhäuser Verlag Basel/Switzerland 2006

Authors and Affiliations

  • Celina M. H. de Figueiredo
    • 1
  • Frédéric Maffray
    • 2
  • Claudia Regina Villela Maciel
    • 3
  1. 1.Departamento de Ciência da Computação, Instituto de MatemáticaUniversidade Federal do Rio de JaneiroRio de Janeiro, RJBrazil
  2. 2.Laboratoire LeibnizCNRSGrenoble CedexFrance
  3. 3.Instituto de MatemáticaUniversidade Federal FluminenseNiterói, RJBrazil

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