Linearity of grid minors in treewidth with applications through bidimensionality

  • Authors:
  • Erik D. Demaine;Mohammadtaghi Hajiaghayi

  • Affiliations:
  • MIT, Computer Science and Artificial Intelligence Laboratory, Cambridge, USA 02139;MIT, Computer Science and Artificial Intelligence Laboratory, Cambridge, USA 02139

  • Venue:
  • Combinatorica
  • Year:
  • 2008

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Abstract

We prove that any H-minor-free graph, for a fixed graph H, of treewidth w has an 驴(w) 脳 驴(w) grid graph as a minor. Thus grid minors suffice to certify that H-minorfree graphs have large treewidth, up to constant factors. This strong relationship was previously known for the special cases of planar graphs and bounded-genus graphs, and is known not to hold for general graphs. The approach of this paper can be viewed more generally as a framework for extending combinatorial results on planar graphs to hold on H-minor-free graphs for any fixed H. Our result has many combinatorial consequences on bidimensionality theory, parameter-treewidth bounds, separator theorems, and bounded local treewidth; each of these combinatorial results has several algorithmic consequences including subexponential fixed-parameter algorithms and approximation algorithms.