Social cognitive optimization


Social cognitive optimization is a population-based metaheuristic optimization algorithm which was developed in 2002. This algorithm is based on the social cognitive theory, and the key point of the ergodicity is the process of individual learning of a set of agents with their own memory and their social learning with the knowledge points in the social sharing library. It has been used for solving continuous optimization, integer programming, and combinatorial optimization problems. It has been incorporated into the extension of Calc in Apache OpenOffice.

Algorithm

Let be a global optimization problem, where is a state in the problem space. In SCO, each state is called a knowledge point, and the function is the goodness function.
In SCO, there are a population of cognitive agents solving in parallel, with a social sharing library. Each agent holds a private memory containing one knowledge point, and the social sharing library contains a set of knowledge points. The algorithm runs in T iterative learning cycles. By running as a Markov chain process, the system behavior in the tth cycle only depends on the system status in the th cycle. The process flow is in follows:
SCO has three main parameters, i.e., the number of agents, the size of social sharing library, and the learning cycle. With the initialization process, the total number of knowledge points to be generated is, and is not related too much with if is large.
Compared to traditional swarm algorithms, e.g. particle swarm optimization, SCO can achieving high-quality solutions as is small, even as. Nevertheless, smaller and might lead to premature convergence. Some variants were proposed to guaranteed the global convergence. One can also make a hybrid optimization method using SCO combined with other optimizers. For example, SCO was hybridized with differential evolution to obtain better results than individual algorithms on a common set of benchmark problems.