Tracking Semantic Evolutionary Changes in Large-Scale Ontological Knowledge Bases

This paper is concerned with the problem of computing the semantic difference between different versions of large-scale ontological knowledge bases using a uniform interpolation (UI) approach. The semantic difference between two versions of an ontology are the axioms entailed by one version but not the other version, reflecting the evolutionary changes of the content of the ontology. In general, computing such axioms is not computationally feasible, since there are infinitely many of them. UI is an advanced reasoning technique that seeks to create restricted views of ontologies; it provides an effective means for computing a finite representation of the difference between two ontologies. While existing UI methods are designed for languages that are either more expressive or less expressive than the description logic ELH, the underlying language of typical large-scale ontologies, in this paper, we introduce a practical UI method tailored for the task of computing the semantic difference in large-scale ELH-ontologies. The method is terminating, sound, and can always compute UI results possibly including fresh definer symbols. Two case studies on different versions of the SNOMED CT terminology show that the method has overcome major limitations of existing UI methods and can be used to reveal modeling changes that have occurred over successive releases of SNOMED CT.