When Maximum Stable Set Can Be Solved in FPT Time

Edouard Bonnet (1) , Nicolas Bousquet (2) , Stéphan Thomassé (1, 3) , Rémi Watrigant (1)

1 MC2 - Modèles de calcul, Complexité, Combinatoire
2 GOAL - Graphes, AlgOrithmes et AppLications
3 IUF - Institut universitaire de France

Maximum Independent Set (MIS for short) is in general graphs the paradigmatic W [1]-hard problem. In stark contrast, polynomial-time algorithms are known when the inputs are restricted to structured graph classes such as, for instance, perfect graphs (which includes bipartite graphs, chordal graphs, co-graphs, etc.) or claw-free graphs. In this paper, we introduce some variants of co-graphs with parameterized noise, that is, graphs that can be made into disjoint unions or complete sums by the removal of a certain number of vertices and the addition/deletion of a certain number of edges per incident vertex, both controlled by the parameter. We give a series of FPT Turing-reductions on these classes and use them to make some progress on the parameterized complexity of MIS in H-free graphs. We show that for every fixed t 1, MIS is FPT in P (1, t, t, t)-free graphs, where P (1, t, t, t) is the graph obtained by substituting all the vertices of a four-vertex path but one end of the path by cliques of size t. We also provide randomized FPT algorithms in dart-free graphs and in cricket-free graphs. This settles the FPT/W[1]-hard dichotomy for five-vertex graphs H. 2012 ACM Subject Classification Theory of computation → Graph algorithms analysis; Theory of computation → Fixed parameter tractability

Mots clés: and phrases Parameterized Algorithms; Independent Set; H-Free Graphs

Domaines: Mathématique discrète [cs.DM]

Edouard Bonnet, Nicolas Bousquet, Stéphan Thomassé, Rémi Watrigant. When Maximum Stable Set Can Be Solved in FPT Time. 30th International Symposium on Algorithms and Computation (ISAAC 2019), Dec 2019, Shanghai, China. ⟨10.4230/LIPIcs.ISAAC.2019.49⟩. ⟨hal-02935501⟩