Integration of subgraph isomorphism problem into ALGator system

Peter Remec (2015) Integration of subgraph isomorphism problem into ALGator system. EngD thesis.

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Abstract

This thesis deals with a subgraph isomorphism problem and its integration into ALGator system. Detection of isomorphic subgraph is present in many scientific fields nowadays, therefore new problem solving algorithms constantly appear. We focus on a detailed description of Ullmann algorithm, improved Ullmann algorithm and RI algorithm, the most recent among listed. Those algorithms, which are suitable for isomorphism detection in directed or undirected unlabeled graphs, were implemented in Java programming language for the purpose of integration into ALGator. The system is intended for the use of algorithm development researchers, providing simplified testing of algorithm's efficiency and analysis of testing results. We have applied system functionalities on the selected problem. In addition to a problem definition we have included all the implemented algorithms into ALGator project (improved Ullmann algorithm is given in two versions) and observed their efficiency. We have executed the experiment on more than 50000 different pairs of graphs. The analysis of testing results with ALGator shows, that RI algorithm is the fastest one among all four algorithms. On the other hand Ullmann algorithm performed the worst, while the performance of its improved versions were even comparable with RI algorithm in certain scenarios. By integrating the problem into ALGator we have presented its capabilities and proposed some improvements.

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