A Novel Quantum Genetic Algorithm for TSP

Quantum genetic algorithm(QGA) was proved to be better than the conventional genetic algorithms on numerical and combinational optimization problems,but it is usually used to solve the knapsack problems of the combinational optimization.It is also possible to use its strong ability of exploitation and exploration to other difficult problems,for example,the TSP,a class of NP-hard combinatorial optimization problems.First,a new encoding scheme with pairs of amplitudes is designed.A quantum individual is corresponding to a vector,and the vector is corresponding to the unique valid tour,and vice versa.The advantages of the encoding scheme are that it always generates feasible solution,uses less population size and storage,and can effectively enhance the diversity of the population.Second,the quantum crossover can maintain the relatively good gene blocks.Third,the two-phase local search for edge evolving is integrated into QGA to accelerate its convergent speed.The first phase is used to optimize the sparsely located cities,and the second phase is used to optimize densely located cities.Based on these,a novel and efficient QGA for TSP is proposed,and its convergence to global optimal solution with probability one is proved.The numerical experiments show that the proposed algorithm can find the global optimal solution with less computation and evolving time.