Interval Tournaments

✍ Scribed by David E. Brown; Arthur H. Busch; J. Richard Lundgren

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 192 KB
• Volume: 56
• Category: Article
• ISSN: 0364-9024
• DOI: 10.1002/jgt.20247

✦ Synopsis

Abstract

A tournament is an orientation of a complete graph. A directed graph is an interval digraph if for each vertex v there corresponds an ordered pair of intervals (S~v~, T~v~) such that u → v if and only if S~u~ ∩ T~v~ ≠ ∅︁. A bipartite graph is an interval bigraph if to each vertex there corresponds an interval such that vertices are adjacent if and only if their corresponding intervals intersect and each vertex belongs to a different partite set. We use the equivalence of the models for interval digraphs and interval bigraphs to characterize tournaments that are interval digraphs via forbidden subtournaments and prove that a tournament on n vertices is an interval digraph if and only if it has a transitive (n − 1)‐subtournament. We also characterize the obstructions to the existence of a transitive subtournament of order n − 1 in a tournament of order n. © 2007 Wiley Periodicals, Inc. J Graph Theory 56: 72–81, 2007