Inseparability and Conservative Extensions of Description Logic Ontologies: A Survey

TL;DR

This survey reviews various notions of inseparability in description logic ontologies, focusing on their theoretical foundations, applications, algorithms for checking inseparability, and computational complexity.

Contribution

It provides a comprehensive overview of different inseparability notions, their model-theoretic characterizations, and algorithmic approaches in the context of description logic ontologies.

Findings

Different notions of inseparability are characterized and compared.

Algorithms for checking inseparability are discussed.

Complexity results for inseparability problems are summarized.

Abstract

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.