Large-Treewidth Graph Decompositions and Applications
arXiv:1304.1577
Abstract
Treewidth is a graph parameter that plays a fundamental role in several structural and algorithmic results. We study the problem of decomposing a given graph into node-disjoint subgraphs, where each subgraph has sufficiently large treewidth. We prove two theorems on the tradeoff between the number of the desired subgraphs , and the desired lower bound on the treewidth of each subgraph. The theorems assert that, given a graph with treewidth , a decomposition with parameters is feasible whenever $hr^2 \le k/\polylog(k)$, or $h^3r \le k/\polylog(k)$ holds. We then show a framework for using these theorems to bypass the well-known Grid-Minor Theorem of Robertson and Seymour in some applications. In particular, this leads to substantially improved parameters in some Erdos-Posa-type results, and faster algorithms for a class of fixed-parameter tractable problems.
An extended abstract of the paper is to appear in Proceedings of ACM STOC, 2013