Inseparability and Conservative Extensions of Description Logic Ontologies: A Survey
This work provides a comprehensive overview for ontology engineers and researchers, but it is incremental as it synthesizes existing results without introducing new methods.
The paper surveys various notions of inseparability and conservative extensions in description logic ontologies, addressing the problem of safely replacing ontologies in tasks like versioning and modularization, and discusses applications, characterizations, algorithms, and computational complexity.
The question whether an ontology can safely be replaced by another, possibly simpler, one is fundamental for many ontology engineering and maintenance tasks. It underpins, for example, ontology versioning, ontology modularization, forgetting, and knowledge exchange. What safe replacement means depends on the intended application of the ontology. If, for example, it is used to query data, then the answers to any relevant ontology-mediated query should be the same over any relevant data set; if, in contrast, the ontology is used for conceptual reasoning, then the entailed subsumptions between concept expressions should coincide. This gives rise to different notions of ontology inseparability such as query inseparability and concept inseparability, which generalize corresponding notions of conservative extensions. We survey results on various notions of inseparability in the context of description logic ontologies, discussing their applications, useful model-theoretic characterizations, algorithms for determining whether two ontologies are inseparable (and, sometimes, for computing the difference between them if they are not), and the computational complexity of this problem.