Towards a Better Understanding of the Local Attractor in Particle Swarm Optimization: Speed and Solution Quality

TL;DR

This paper investigates how the local attractor influences exploration and exploitation in Particle Swarm Optimization, revealing that it enhances exploration but may hinder exploitation, leading to a hybrid approach for balanced performance.

Contribution

It provides the first detailed experimental analysis of the local attractor's role in PSO and proposes a hybrid method to optimize its effects.

Findings

Local attractor improves exploration capabilities.

Ignoring local attractor can enhance exploitation quality.

Hybrid PSO switching off local attractors balances exploration and exploitation.

Abstract

Particle Swarm Optimization (PSO) is a popular nature-inspired meta-heuristic for solving continuous optimization problems. Although this technique is widely used, the understanding of the mechanisms that make swarms so successful is still limited. We present the first substantial experimental investigation of the influence of the local attractor on the quality of exploration and exploitation. We compare in detail classical PSO with the social-only variant where local attractors are ignored. To measure the exploration capabilities, we determine how frequently both variants return results in the neighborhood of the global optimum. We measure the quality of exploitation by considering only function values from runs that reached a search point sufficiently close to the global optimum and then comparing in how many digits such values still deviate from the global minimum value. It turns out that the local attractor significantly improves the exploration, but sometimes reduces the quality of the exploitation. As a compromise, we propose and evaluate a hybrid PSO which switches off its local attractors at a certain point in time. The effects mentioned can also be observed by measuring the potential of the swarm.