Node deletion sequences in influence diagrams using genetic algorithms

  • Authors:
  • M. Gómez;C. Bielza

  • Affiliations:
  • Department of Computer Science and Artificial Intelligence, University of Granada, Spain. mgomez@decsai.ugr.es;Department of Artificial Intelligence, Technical University of Madrid, Spain. mcbielza@fi.upm.es

  • Venue:
  • Statistics and Computing
  • Year:
  • 2004

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Abstract

Influence diagrams are powerful tools for representing and solving complex inference and decision-making problems under uncertainty. They are directed acyclic graphs with nodes and arcs that have a precise meaning. The algorithm for evaluating an influence diagram deletes nodes from the graph in a particular order given by the position of each node and its arcs with respect to the value node. In many cases, however, there is more than one possible node deletion sequence. They all lead to the optimal solution of the problem, but may involve different computational efforts, which is a primary issue when facing real-size models. Finding the optimal deletion sequence is a NP-hard problem. The proposals given in the literature have proven to require complex transformations of the influence diagram. In this paper, we present a genetic algorithm-based approach, which merely has to be added to the influence diagram evaluation algorithm we use, and whose codification is straightforward. The experiments, varying parameters like crossover and mutation operators, population sizes and mutation rates, are analysed statistically, showing favourable results over existing heuristics.