A Polymorphic Ant-Based Algorithm for Graph Clustering
Liu, Ying Ying
Liu, Ying Ying
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In this thesis, I introduce two new algorithms: Ant Brood Clustering-Intelligent Ants (ABC-INTE) and Ant Brood Clustering-Polymorphic Ants (ABC-POLY) for the graph clustering problem. ABC-INTE uses techniques such as hopping ants, relaxed drop function, ants with memories, stagnation control, and addition of k-means cluster retrieval process, as an improvement of the basic ABC-KLS algorithm. ABC-POLY uses two types of ants, inspired by the division of labour between the major and minor ants in Pheidole genus, as an improvement of ABC-INTE. For comparison purpose, I also implement MMAS, an ACO clustering algorithm. When tested on the benchmark networks, ABC-POLY outperforms or achieves the same modularity values as MMAS and ABC-INTE on 7 out of 10 networks and is robust against different graphs. In practice, the speed of ABC-POLY is at least 10 times faster than MMAS, making it a scalable algorithm compared to MMAS. ABC-POLY also outputs a direct visual representation of the natural clusters on the graph that is appealing to human observation. This thesis opens an interesting research topic to apply polymorphic ants for graph clustering in the ABC-POLY algorithm. The distributive and self-organization nature of ABC-POLY makes it a candidate for analyzing clusters in more complex and dynamic graphs.