Analysis of Evolutionary Diversity Optimisation for the Maximum Matching Problem
Jonathan Gadea Harder, Aneta Neumann, Frank Neumann
TL;DR
This work investigates evolutionary diversity optimization (EDO) for the maximum matching problem on complete bipartite graphs and path graphs, using binary string encoding and Hamming distance to quantify diversity. It analyzes two population-based algorithms, the (μ+1)-EA_D and the Two-Phase Matching EA_D (2P-EA_D), providing drift-theorem–based runtime bounds and supporting empirical evidence. The theoretical results show polynomial-time convergence to a maximally diverse population of high-quality matchings, with distinct bounds depending on the graph structure and gap between partitions; the 2P-EA_D generally yields tighter runtimes. Empirical experiments corroborate the theory and indicate potential refinements to the bounds, while demonstrating the practical relevance of maintaining diverse, high-quality matchings for decision-making in combinatorial settings.
Abstract
This paper explores the enhancement of solution diversity in evolutionary algorithms (EAs) for the maximum matching problem, concentrating on complete bipartite graphs and paths. We adopt binary string encoding for matchings and use Hamming distance to measure diversity, aiming for its maximization. Our study centers on the $(μ+1)$-EA and $2P-EA_D$, which are applied to optimize diversity. We provide a rigorous theoretical and empirical analysis of these algorithms. For complete bipartite graphs, our runtime analysis shows that, with a reasonably small $μ$, the $(μ+1)$-EA achieves maximal diversity with an expected runtime of $O(μ^2 m^4 \log(m))$ for the small gap case (where the population size $μ$ is less than the difference in the sizes of the bipartite partitions) and $O(μ^2 m^2 \log(m))$ otherwise. For paths, we establish an upper runtime bound of $O(μ^3 m^3)$. The $2P-EA_D$ displays stronger performance, with bounds of $O(μ^2 m^2 \log(m))$ for the small gap case, $O(μ^2 n^2 \log(n))$ otherwise, and $O(μ^3 m^2)$ for paths. Here, $n$ represents the total number of vertices and $m$ the number of edges. Our empirical studies, which examine the scaling behavior with respect to $m$ and $μ$, complement these theoretical insights and suggest potential for further refinement of the runtime bounds.
