Terminological Cycles in a Description Logic with Existential Restrictions

Cyclic definitions in description logics have until now been investigated only for description logics allowing for value restrictions. Even for the most basic language which allows for conjunction and value restrictions only, deciding subsumption in the presence of terminological cycles is a PSPACE-complete problem. This paper investigates subsumption in the presence of terminological cycles for the language . , which allows for conjunction, existential restrictions, and the topconcept. In contrast to the results for , subsumption in remains polynomial, independent of whether we use least fixpoint semantics, greatest fixpoint semantics, or descriptive semantics.

• Type: Conference
• Year: 2003
• Where: IJCAI
• Authors: Franz Baader
• Keywords: Description Logics, IJCAI 2003, IJCAI 2007, Terminological Cycles, Value Restrictions