Preferential Attachment in Constraint Networks

  • Authors:
  • David Devlin;Barry O'Sullivan

  • Affiliations:
  • -;-

  • Venue:
  • ICTAI '09 Proceedings of the 2009 21st IEEE International Conference on Tools with Artificial Intelligence
  • Year:
  • 2009

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Abstract

Many complex real-world systems can be modeled using a graphicalstructure such as a constraint network. If the properties of sucha structure can be exploited, many challenging computationaltasks can have good typical-case runtimes even if theyare theoretically intractable in general. In this paper we show that many real-world constraint networks induce binary networks that share a common underlying structural characterisation; namely, that their degree distributionsexhibit preferential attachment. We report on a novel constraint network generator for randomconstraint networks that have a scale-free macrostructure. This scale-free generator is based on the well known Barabasi-Albert preferential attachment model. Using this model we demonstrate that real-world constraint networksexhibit degree distributions that are more like those found inscale-free graphs. We also show that the effect of standard degree-based search heuristics on real-world problems exhibiting power-law degree distributions is greater than problems with a uniform random structure. We also show that the backdoor sizes for preferentially attached constraint networks are smaller than those of uniform randomproblems. This paper provides a novel basis for studying realistic constraintmodels.