Paths and cycles containing given arcs, in close to regular multipartite tournaments

  • Authors:
  • Anders Yeo

  • Affiliations:
  • Department of Computer Science, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK

  • Venue:
  • Journal of Combinatorial Theory Series B
  • Year:
  • 2007

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Abstract

The global irregularity of a digraph D is defined by i"g(D)=max{d^+(x),d^-(x)}-min{d^+(y),d^-(y)} over all vertices x and y of D (including x=y). In this paper we prove that if D is a c-partite tournament such that c=4 and |V(D)|476i"g(D)+13917 then there exists a path of length l between any two given vertices for all 42==4 have a Hamilton cycle through any given arc, and the condition c=4 is best possible. Sufficient conditions are furthermore given for when a c-partite tournament with c=4 has a Hamilton cycle containing a given path or a set of given arcs. We show that all sufficiently large c-partite tournaments with c=5 and bounded i"g are vertex-pancyclic and all sufficiently large regular 4-partite tournaments are vertex-pancyclic. Finally we give a lower bound on the number of Hamilton cycles in a c-partite tournament with c=4.