This paper proposes a new smart crossover operator for a Pittsburgh Learning Classifier System. This operator, unlike other recent LCS approaches of smart recombination, does not learn the structure of the domain, but it merges the rules of N parents ( N  ≥ 2) to generate a new offspring. This merge process uses an heuristic that selects the minimum subset of candidate rules that obtains maximum training accuracy. Moreover the operator also includes a rule pruning scheme to avoid the inclusion of over-specific rules, and to guarantee as much as possible the robust behaviour of the LCS. This operator takes advantage from the fact that each individual in a Pittsburgh LCS is a complete solution, and the system has a global view of the solution space that the proposed rule selection algorithm exploits. We have empirically evaluated this operator using a recent LCS called GAssist. First with the standard LCS benchmark, the 11 bits multiplexer, and later using 25 standard real datasets. The results of the experiments over these datasets indicate that the new operator manages to increase the accuracy of the system over the classical crossover in 16 of the 25 datasets, and never having a significantly worse performance than the classic operator.
['Jaume Bacardit', 'Natalio Krasnogor']
Smart crossover operator with multiple parents for a Pittsburgh learning classifier system