Improved Dynamics for the Maximum Common Subgraph Problem

The Maximum Common Subgraph (MCS) problem plays a crucial role across various domains, bridging theoretical exploration and practical applications in fields like bioinformatics and social network analysis. Despite its wide applicability, MCS is notoriously challenging and is classified as an NP-Complete (NPC) problem. This study introduces new heuristics aimed at mitigating these challenges through the reformulation of the MCS problem as the Maximum Clique and its complement, the Maximum Independent Set. Our first heuristic leverages the Motzkin-Straus theorem to reformulate the Maximum Clique Problem as a constrained optimization problem, continuing the work of Pelillo in Replicator Equations, Maximal Cliques, and Graph Isomorphism (1999) with replicator dynamics and introducing annealed imitation heuristics as in Dominant Sets and Hierarchical Clustering (Pavan and Pelillo, 2003) to improve chances of convergence to better local optima. The second technique applies heuristics drawn upon strategies for the Maximum Independent Set problem to efficiently reduce graph sizes as used by Akiwa and Iwata in 2014. This enables faster computation and, in many instances, yields near-optimal solutions. Furthermore we look at the implementation of both techniques in a single algorithm and find that it is a promising approach. Our techniques were tested on randomly generated Erd\H{o}s-R\'enyi graph pairs. Results indicate the potential for application and substantial impact on future research directions.