Particle Swarm Optimization - A Survey <s> Diversity <s> Particle swarm optimisers (PSOs) show potential in function optimisation, but still have room for improvement. Self-organized criticality (SOC) can help control the PSO and add diversity. Extending the PSO with SOC seems promising reaching faster convergence and better solutions. <s> BIB001 </s> Particle Swarm Optimization - A Survey <s> Diversity <s> Multi-phase particle swarm optimization is a new algorithm to be used for discrete and continuous problems. In this algorithm, different groups of particles have trajectories that proceed with differing goals in different phases of the algorithm. On several benchmark problems, the algorithm outperforms standard particle swarm optimization, genetic algorithm, and evolution programming. <s> BIB002 </s> Particle Swarm Optimization - A Survey <s> Diversity <s> An important factor contributing to the success of particle swarm optimization (PSO) is the balance between exploration and exploitation of the swarm. Exploration is typically preferred at the initial stages of the search but is required to gradually give way to exploitation of promising solutions as the search progresses. The diversity of a particle swarm optimization algorithm can be defined, simply, as the degree of dispersion of the particles in the swarm. This dispersion could be defined around some center-point or not. It could also be defined based on the positions of the particles or on their velocities. This paper takes a look at some of the different definitions of swarm diversity with the intention of determining their usefulness in quantifying swarm exploration/exploitation. This work is intended to lay the foundations for the development of a suitable means to quantify the rate of change from exploration to exploitation of a PSO, i.e. the rate of change of diversity. <s> BIB003
Maintenance of diversity is also important in finding a good solution in a high-dimensional search domain. Delayed information propagation by sparsely connected neighborhoods contributes in this aspect. Other modifications specially aimed for the maintenance of diversity include particle replacement from a dense cluster (Løvbjerg and Krink BIB001 ), use of repulsion force to avoid particle collision (Krink et al.  ), and occasional switching of dynamics among the sub-swarms (Al-kazemi and Mohan BIB002 ). Stochastic switching of particle dynamics with a similar aim is found in Vesterstrøm et al.  . See Olorunda and Engelbrecht BIB003 for various definitions of swarm diversity and their features.