On Population-Based Algorithms for Distributed Constraint Optimization Problems

TL;DR

This paper introduces two novel population-based algorithms, AED and DPSA, for distributed constraint optimization problems, demonstrating significant improvements over existing methods in solution quality through extensive empirical evaluation.

Contribution

The paper presents two new population-based algorithms, AED and DPSA, combining evolutionary and local search techniques to enhance solution quality for DCOPs.

Findings

AED and DPSA outperform existing algorithms by up to 75% in solution quality.

Both algorithms effectively explore large search spaces and avoid local optima.

Empirical results validate the superiority of the proposed methods across various benchmarks.

Abstract

Distributed Constraint Optimization Problems (DCOPs) are a widely studied class of optimization problems in which interaction between a set of cooperative agents are modeled as a set of constraints. DCOPs are NP-hard and significant effort has been devoted to developing methods for finding incomplete solutions. In this paper, we study an emerging class of such incomplete algorithms that are broadly termed as population-based algorithms. The main characteristic of these algorithms is that they maintain a population of candidate solutions of a given problem and use this population to cover a large area of the search space and to avoid local-optima. In recent years, this class of algorithms has gained significant attention due to their ability to produce high-quality incomplete solutions. With the primary goal of further improving the quality of solutions compared to the state-of-the-art incomplete DCOP algorithms, we present two new population-based algorithms in this paper. Our first approach, Anytime Evolutionary DCOP or AED, exploits evolutionary optimization meta-heuristics to solve DCOPs. We also present a novel anytime update mechanism that gives AED its anytime property. While in our second contribution, we show that population-based approaches can be combined with local search approaches. Specifically, we develop an algorithm called DPSA based on the Simulated Annealing meta-heuristic. We empirically evaluate these two algorithms to illustrate their respective effectiveness in different settings against the state-of-the-art incomplete DCOP algorithms including all existing population-based algorithms in a wide variety of benchmarks. Our evaluation shows AED and DPSA markedly outperform the state-of-the-art and produce up to 75% improved solutions.