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arXiv · 2003.05185

Induced subgraphs of bounded treewidth and the container method

Tara Abrishami·Maria Chudnovsky·Marcin Pilipczuk·Paweł Rzążewski·Paul Seymour
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Abstract

A hole in a graph is an induced cycle of length at least 4. A hole is long if its length is at least 5. By $P_t$ we denote a path on $t$ vertices. In this paper we give polynomial-time algorithms for the following problems: the Maximum Weight Independent Set problem in long-hole-free graphs, and the Feedback Vertex Set problem in $P_5$-free graphs. Each of the above results resolves a corresponding long-standing open problem. An extended $C_5$ is a five-vertex hole with an additional vertex adjacent to one or two consecutive vertices of the hole. Let $\mathcal{C}$ be the class of graphs excluding an extended $C_5$ and holes of length at least $6$ as induced subgraphs; $\mathcal{C}$ contains all long-hole-free graphs and all $P_5$-free graphs. We show that, given an $n$-vertex graph $G \in \mathcal{C}$ with vertex weights and an integer $k$, one can in time $n^{\Oh(k)}$ find a maximum-weight induced subgraph of $G$ of treewidth less than $k$. This implies both aforementioned results.

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Tara Abrishami, Maria Chudnovsky, Marcin Pilipczuk, Paweł Rzążewski, Paul Seymour. 2020-03-11. Induced subgraphs of bounded treewidth and the container method. https://arxiv.org/abs/2003.05185

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