A Hybrid System with Datalogand Concept Languages Francesco

We present a hybrid system for knowledge representation, called AL-log, based on the concept language ALC and the deductive database language Datalog. AL-log embodies two subsystems, called structural and relational. The former allows for the deenition of structural knowledge about the classes of interest and the membership relation between objects and classes. The latter allows for the deenition of re-lational knowledge about the objects described in the structural component. The interaction between the two components is obtained by allowing ALC-constraints within Datalog clauses, thus requiring the variables in the clauses to range over the set of instances of a speciied concept. We propose a method for hybrid reasoning based on constrained resolution, where the usual deduction procedure deened for Datalog is integrated with a method for reasoning on the structural knowledge.