Approximation of Boolean Functions by Local Search

  • Authors:
  • Andreas Albrecht;Chak-Kuen Wong

  • Affiliations:
  • Department of Computer Science, University of Hertfordshire, Hatfield, Herts AL10 9AB, UK. a.albrecht@herts.ac.uk;Department of Computer Science and Engineering, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong

  • Venue:
  • Computational Optimization and Applications
  • Year:
  • 2004

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Abstract

Usually, local search methods are considered to be slow. In our paper, we present a simulated annealing-based local search algorithm for the approximation of Boolean functions with a proven time complexity that behaves relatively fast on randomly generated functions. The functions are represented by disjunctive normal forms (DNFs). Given a set of m uniformly distributed positive and negative examples of length n generated by a target function F(x1,…,xn), where the DNF consists of conjunctions with at most ℓ literals only, the algorithm computes with high probability a hypothesis H of length m · ℓ such that the error is zero on all examples. Our algorithm can be implemented easily and we obtained a relatively high percentage of correct classifications on test examples that were not presented in the learning phase. For example, for randomly generated F with n = 64 variables and a training set of m = 16384 examples, the error on the same number of test examples was about 19% on positive and 29% on negative examples, respectively. The proven complexity bound provides the basis for further studies on the average case complexity.