Reduced error pruning of branching programs cannot be approximated to within a logarithmic factor

  • Authors:
  • Richard Nock;Tapio Elomaa;Matti Kääriäinen

  • Affiliations:
  • Département Scientifique Interfacultaire, Université des Antilles-Guyane, Campus de Schoelcher, BP 7209, 97275 Schoelcher, Martinique, France;Department of Computer Science, P.O. Box 26 (Teollisuuskatu 23), FIN-00014 University of Helsinki, Finland;Department of Computer Science, P.O. Box 26 (Teollisuuskatu 23), FIN-00014 University of Helsinki, Finland

  • Venue:
  • Information Processing Letters
  • Year:
  • 2003

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Abstract

In this paper, we prove under a plausible complexity hypothesis that Reduced Error Pruning of branching programs is hard to approximate within log1-δ n, for every δ 0, where n is the number of description variables, a measure of the problem's complexity. The result holds under the assumption that NP problems do not admit deterministic, slightly superpolynomial time algorithms: NP ⊄ TIME(|I|O(loglog |I|)). This improves on a previous result that only had a small constant inapproximability ratio, and puts a fairly strong constraint on the efficiency of potential approximation algorithms. The result also holds for read-once and µ-branching programs.