Maximal Biclique Enumeration


Integrating and analyzing heterogeneous genome-scale data is a huge algorithmic challenge for modern systems biology. Bipartite graphs can be useful for representing relationships across pairs of disparate data types, with the interpretation of these relationships accomplished through an enumeration of maximal bicliques. Most previously-known techniques are generally ill-suited to this foundational task, because they are relatively inefficient and without effective scaling. In recent work, we have devised a powerful new algorithm that produces all maximal bicliques in a bipartite graph. Unlike most previous approaches, the new method neither places undue restrictions on its input nor inflates the problem size. Efficiency is achieved through an innovative exploitation of bipartite graph structure, and through computational reductions that rapidly eliminate non-maximal candidates from the search space. An iterative selection of vertices for consideration based on non-decreasing common neighborhood sizes boosts efficiency and leads to more balanced recursion trees.


The new technique was implemented in C on Ubuntu Linux and compared to previously published approaches from graph theory and data mining. Formal time and space bounds were derived. Experiments were performed on both random graphs and graphs constructed from functional genomics data. It was found that the new method substantially outperforms the best previous alternatives.


The new method is streamlined, efficient, and particularly well-suited to the study of huge and diverse biological data. A robust implementation has been incorporated into GeneWeaver, an online tool for integrating and analyzing functional genomics experiments. The enormous increase in scalability it provides empowers users to study complex and previously unassailable gene-set associations between genes and their biological functions in a hierarchical fashion and on a genome-wide scale. This practical computational resource is adaptable to almost any applications environment in which bipartite graphs can be used to model relationships between pairs of heterogeneous entities.

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Y. Zhang, C. A. Phillips, G. L. Rogers, E. J. Baker, E. J. Chesler and M. A. Langston, "On Finding Bicliques in Bipartite Graphs: a Novel Algorithm and Its Application to the Integration of Diverse Biological Data Types," BMC Bioinformatics, accepted for publication.


Available upon request.