Clustering with local restrictions

  • Authors:
  • Daniel Lokshtanov;Dániel Marx

  • Affiliations:
  • University of California, San Diego;Humboldt-Universität zu Berlin, Berlin, Germany

  • Venue:
  • ICALP'11 Proceedings of the 38th international colloquim conference on Automata, languages and programming - Volume Part I
  • Year:
  • 2011

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Abstract

We study a family of graph clustering problems where each cluster has to satisfy a certain local requirement. Formally, let µ be a function on the subsets of vertices of a graph G. In the (µ, p, q)- Partition problem, the task is to find a partition of the vertices into clusters where each cluster C satisfies the requirements that (1) at most q edges leave C and (2) µ(C) ≤ p. Our first result shows that if µ is an arbitrary polynomial-time computable monotone function, then (µ, p, q)- Partition can be solved in time nO(q), i.e., it is polynomial-time solvable for every fixed q. We study in detail three concrete functions µ (number of nonedges in the cluster, maximum number of non-neighbours a vertex has in the cluster, the number of vertices in the cluster), which correspond to natural clustering problems. For these functions, we show that (µ, p, q)-Partition can be solved in time 2O(p) ċ nO(1) and in randomized time 2O(q) ċ nO(1), i.e., the problem is fixed-parameter tractable parameterized by p or by q.