Computing Least Common Subsumers in Description Logics with Existential Restrictions

Franz Baader, Ralf Küsters, Ralf Molitor

Abstract: Computing the least common subsunier (les) is an inference task that can be used to support, the "bottom-up" construction of knowledge bases for KR systems based on description logics. Previous work on how to compute the lcs has concentrated on description logics that allow for universal value restrictions, but not for existential restrictions. The main new contribution of this paper is the treatment of description logics with existential restrictions. Our approach for computing the lcs is based on an appropriate representation of concept descriptions by certain trees, and a characterization of subsumption by homomorphisins between these trees. The lcs operation then corresponds to the product operation on trees.