Stagnation analysis of swarm intelligent algorithms

The search progress of swarm intelligent algorithms is a kind of complex system evolution. Definitions of pure diversification search and pure intensification search are first given based on detail analysis on search characteristics of swarm intelligent algorithms. Then the pure intensification search is recognized as the essential reason of stagnation based on a detail quantitative on the degree of population diversity. Along with the degree of population diversity decreases, the stagnation is apt to occurs. Moreover, the stagnation is related with the population size. The smaller population size is, the easier swarm intelligent algorithms come to a standstill.