title: Exploring biomedical ontology mappings with graph theory methods.
abstract: BACKGROUND
  In the era of semantic web, life science ontologies play an important role in tasks such as annotating biological objects, linking relevant data pieces, and verifying data consistency. Understanding ontology structures and overlapping ontologies is essential for tasks such as ontology reuse and development. We present an exploratory study where we examine structure and look for patterns in BioPortal, a comprehensive publicly available repository of live science ontologies.
  
  
  METHODS
  We report an analysis of biomedical ontology mapping data over time. We apply graph theory methods such as Modularity Analysis and Betweenness Centrality to analyse data gathered at five different time points. We identify communities, i.e., sets of overlapping ontologies, and define similar and closest communities. We demonstrate evolution of identified communities over time and identify core ontologies of the closest communities. We use BioPortal project and category data to measure community coherence. We also validate identified communities with their mutual mentions in scientific literature.
  
  
  RESULTS
  With comparing mapping data gathered at five different time points, we identified similar and closest communities of overlapping ontologies, and demonstrated evolution of communities over time. Results showed that anatomy and health ontologies tend to form more isolated communities compared to other categories. We also showed that communities contain all or the majority of ontologies being used in narrower projects. In addition, we identified major changes in mapping data after migration to BioPortal Version 4.
authors.affiliation: Database Center for Life Science, Research Organization of Information and Systems, Tokyo, Japan; Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW, Australia; Department of Computing and Information Systems, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Simon
authors.initials: S
authors.lastname: Kocbek
authors.affiliation: Database Center for Life Science, Research Organization of Information and Systems , Tokyo , Japan.
authors.forename: Jin-Dong
authors.initials: JD
authors.lastname: Kim
keywords: Biomedical ontology; Graph theory; Ontology evolution; Ontology mappings; Semantic web