Partitioning the nodes of a graph to minimize the sum of subgraph radii

  • Authors:
  • Guido Proietti;Peter Widmayer

  • Affiliations:
  • Dipartimento di Informatica, Università di L'Aquila, L'Aquila, Italy;Institut für Theoretische Informatik, ETH, Zürich, Switzerland

  • Venue:
  • ISAAC'06 Proceedings of the 17th international conference on Algorithms and Computation
  • Year:
  • 2006

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Abstract

Let G=(V,E) denote a weighted graph of n nodes and m edges, and let G[ V ′ ] denote the subgraph of G induced by a subset of nodes V′⊆V. The radius of G[ V ′ ] is the maximum length of a shortest path in G[ V ′ ] emanating from its center (i.e., a node of G[ V ′ ] of minimum eccentricity). In this paper, we focus on the problem of partitioning the nodes of G into exactly p non-empty subsets, so as to minimize the sum of the induced subgraph radii. We show that this problem – which is of significance in facility location applications – is NP-hard when p is part of the input, but for a fixed constant p 2 it can be solved in O(n2p/p!) time. Moreover, for the notable case p=2, we present an efficient O(mn2+n3 logn) time algorithm.