Summary: G53KRR handout on description logic.
Variety of description logics/ontology languages. This lecture (based on Brachman and
Levesque chapter 9) is only one particular flavour of description logic. There are very many, with
different syntax and expressive power.
Basic idea description logic talks about relationships between concepts (noun phrases).
Precise definition of the syntax of DL :
Logical symbols (apart from brackets etc.):
· concept-forming operators: ALL, EXISTS, FILLS, AND
· connectives: ,
· symbols for numbers (1,2,3,...),
· Atomic concepts: Person, Thing,. . . . Correspond to unary predicates in FOL.
· Roles: :Age, :Employer, :Child, :Arm, . . .. Correspond to binary predicates in FOL.
· Constants: john, mary, roomA7, . . .. Correspond to constants (0-ary functional symbols) in
· atomic concept is a concept
· if r is a role and b is a concept, then [ALL r b] is a concept (e.g. [ALL : Child Girl]