Developing Heuristic for Subgraph Isomorphism Problem

Subgraph isomorphism problem is an NP-hard problem and the available algorithms are of exponential time complexity. Hence these are not efficient for real world applications. A number of heuristic methods are proposed in the literature in this field. Ullmann[6] proposed a solution for subgraph isomorphism problem in 1976, which is being referred till today. Ullmann's algorithm is refined to get better algorithms in current literature. Cordella et al.[7] proposed an algorithm VF2, that improves Ullmann's refinement. In this project, we propose a heuristic to be applied to Ullmann's algorithm in order to reduce the search space. We show that the proposed heuristic performs better than both Ullmann's and VF2 algorithm. The testing is done using a graph generation software[12]. Further the heuristic algorithm is tested on the benchmark data set [4]. Both the experiments show that our proposed heuristics perform better for all type of graphs given in the benchmark data set.