“…These methods include Particle Swarm Optimization (PSO) [2] , Differential Evolution (DE) [7] , Artificial Bee Colony (ABC) [36] , Gravitational Search Algorithm (GSA) [34] , Harmony Search (HS) [28] , and Simultaneous Perturbation Stochastic Approximation (SPSA) [46] . As these methods have initially been developed under assumption that the search space is continuous, the original methods are not effective on binary problems.…”