Refining Concepts in Description Logics

While the problem of learning logic programs has been extensively studied in ILP, the problem of learning in description logics (DLs) has been studied to a lesser extent. Learning in DLs is however worthwhile, since both Horn logic and description logics are widely used knowledge representation formalisms, their expressive powers being incomparable (neither includes the other as a fragment). Unlike most approaches to learning in description logics, which provide bottom-up (and typically overly specific) least generalizations of the examples, this paper addresses learning in DLs using downward (and upward) refinement operators. Technically