A parameterized view on matroid optimization problems

  • Authors:
  • Dániel Marx

  • Affiliations:
  • Institut fürInformatik, Humboldt-Universität zu Berlin, Berlin, Germany

  • Venue:
  • ICALP'06 Proceedings of the 33rd international conference on Automata, Languages and Programming - Volume Part I
  • Year:
  • 2006

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Abstract

Matroid theory gives us powerful techniques for understanding combinatorial optimization problems and for designing polynomial-time algorithms. However, several natural matroid problems, such as 3-matroid intersection, are NP-hard. Here we investigate these problems from the parameterized complexity point of view: instead of the trivial O(nk) time brute force algorithm for finding a k-element solution, we try to give algorithms with uniformly polynomial (i.e., f(k)nO(1)) running time. The main result is that if the ground set of a represented matroid is partitioned into blocks of size ℓ, then we can determine in f(k,ℓ)nO(1) randomized time whether there is an independent set that is the union of k blocks. As consequence, algorithms with similar running time are obtained for other problems such as finding a k-set in the intersection of ℓ matroids, or finding k terminals in a network such that each of them can be connected simultaneously to the source by ℓ disjoint paths.