Minimally non-preperfect graphs of small maximum degree:

Abstract: "A graph G is called preperfect if each induced subgraph G' [subset] G of order at least 2 has two vertices x, y such that either all maximum cliques of G' containing x contain y, or all maximum independent sets of G' containing y contain x, too. Giving a partial answer...

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Bibliographische Detailangaben
Hauptverfasser: Tuza, Zsolt (VerfasserIn), Wagler, Annegret 1968- (VerfasserIn)
Format: Buch
Sprache:English
Veröffentlicht: Berlin Konrad-Zuse-Zentrum für Informationstechnik 1997
Schriftenreihe:Preprint SC / Konrad-Zuse-Zentrum für Informationstechnik Berlin 1997,28
Schlagworte:
Zusammenfassung:Abstract: "A graph G is called preperfect if each induced subgraph G' [subset] G of order at least 2 has two vertices x, y such that either all maximum cliques of G' containing x contain y, or all maximum independent sets of G' containing y contain x, too. Giving a partial answer to a problem of Hammer and Maffray [Combinatorica 13 (1993), 199- 208], we describe new classes of minimally non-preperfect graphs, and prove the following characterizations: (i) A graph of maximum degree 4 is minimally non-preperfect if and only if it is an odd cycle of length at least 5, or the complement of a cycle of length 7, or the line graph of a 3-regular 3-connected bipartite graph. (ii) If a graph G is not an odd cycle and has no isolated vertices, then its line graph is minimally non- perfect if and only if G is bipartite, 3-edge-connected, regular of degree d for some d [> or =] 3, and contains no 3-edge-connected d'-regular subgraph for any 3 [<or =] d' <d."
Beschreibung:17 S.