velocity are represented by n real numbers, and these operators are simply -, *, +, and again +. But all these mathematical objects can be defined in a completely different way, in order to cope with binary problems (or more generally discrete ones), or even combinatorial ones. One approach is to redefine the operators based on sets. See also Artificial bee colony algorithm Bees algorithm Derivative-free optimization Multi-swarm optimization Particle filter Swarm intelligence Fish School Search Dispersive flies optimisation References External links Particle Swarm Central is a repository for information on PSO. Several source codes are freely available. A brief video of particle swarms optimizing three benchmark functions. Simulation of PSO convergence in a two-dimensional space (Matlab). Applications of PSO. Links to PSO source code Metaheuristics Evolutionary algorithms