Optimization by hybridization of a genetic algorithm with constraint satisfaction techniques

The authors introduce a new optimization method based on a genetic algorithm (GA) mixed with constraint satisfaction problem (CSP) techniques. The approach is designed for combinatorial problems whose search spaces are too large and/or objective functions too complex for usual CSP techniques and whose constraints are too complex for conventional genetic algorithm. The main idea is the handling of sub-domains of the CSP variables by the genetic algorithm. The population of the genetic algorithm is made up of strings of sub-domains whose fitness are computed through the resolution of the corresponding "sub-CSPs" which are somehow much easier than the original problem. They provide basic and dedicated recombination and mutation operators with various degrees of robustness. The first set of experimentations adresses a naive formulation of the vehicle routing problem (VRP) and the radio link frequency assignment problem (RLFAP). The results are quite encouraging as one outperforms CSP techniques and genetic algorithm alone.