Clique-Width and Well-Quasi-Ordering of Triangle-Free Graph Classes

  • Konrad K. Dabrowski
  • Vadim V. Lozin
  • Daniël Paulusma
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10520)


Daligault, Rao and Thomassé asked whether every hereditary graph class that is well-quasi-ordered by the induced subgraph relation has bounded clique-width. Lozin, Razgon and Zamaraev (WG 2015) gave a negative answer to this question, but their counterexample is a class that can only be characterised by infinitely many forbidden induced subgraphs. This raises the issue of whether their question has a positive answer for finitely defined hereditary graph classes. Apart from two stubborn cases, this has been confirmed when at most two induced subgraphs \(H_1,H_2\) are forbidden. We confirm it for one of the two stubborn cases, namely for the case \((H_1,H_2)=(\text {triangle},P_2+P_4)\) by proving that the class of \((\text {triangle},P_2+P_4)\)-free graphs has bounded clique-width and is well-quasi-ordered. Our technique is based on a special decomposition of 3-partite graphs. We also use this technique to completely determine which classes of \((\text {triangle},H)\)-free graphs are well-quasi-ordered.


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Konrad K. Dabrowski
    • 1
  • Vadim V. Lozin
    • 2
  • Daniël Paulusma
    • 1
  1. 1.Department of Computer ScienceDurham UniversityDurhamUK
  2. 2.Mathematics InstituteUniversity of WarwickCoventryUK

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