Approximability of partitioning graphs with supply and demand

Takehiro Ito, Erik D. Demaine, Xiao Zhou, Takao Nishizeki

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Suppose that each vertex of a graph G is either a supply vertex or a demand vertex and is assigned a positive real number, called the supply or the demand. Each demand vertex can receive "power" from at most one supply vertex through edges in G. One thus wishes to partition G into connected components by deleting edges from G so that each component C either has no supply vertex or has exactly one supply vertex whose supply is at least the sum of demands in C, and wishes to maximize the fulfillment, that is, the sum of demands in all components with supply vertices. This maximization problem is known to be NP-hard even for trees having exactly one supply vertex and strongly NP-hard for general graphs. In this paper, we focus on the approximability of the problem. We first show that the problem is MAXSNP-hard and hence there is no polynomial-time approximation scheme (PTAS) for general graphs unless P = NP. We then present a fully polynomial-time approximation scheme (FPTAS) for series-parallel graphs having exactly one supply vertex.

Original languageEnglish
Pages (from-to)627-650
Number of pages24
JournalJournal of Discrete Algorithms
Issue number4
Publication statusPublished - 2008 Dec


  • Approximation algorithm
  • Demand
  • Graph partition problem
  • MAXSNP-hard
  • Series-parallel graph
  • Supply

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Discrete Mathematics and Combinatorics
  • Computational Theory and Mathematics


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