A Similarity Measure for the Description Logic EL with Unfoldable Terminologies

Description Logics (DLs) are a family of logic-based knowledge representation formalisms, which can be used to develop ontologies in a formally well-founded way. The standard reasoning service of subsumption has proved indispensable in ontology design and maintenance. This checks, relative to the logical definitions in the ontology, whether one concept is more general/specific than another. When no subsumption relationship is identified, however, no information about the two concepts can be given. This work presents a new notion of semantic similarity which stems from the known homomorphism-based structural subsumption algorithm. The proposed similarity measure computes a numerical degree of similarity between two EL concept descriptions despite not being in the subsumption relation.