  Abductive reasoning generates explanatory hypotheses for new observations
using prior knowledge. This paper investigates the use of forgetting, also
known as uniform interpolation, to perform ABox abduction in description logic
(ALC) ontologies. Non-abducibles are specified by a forgetting signature which
can contain concept, but not role, symbols. The resulting hypotheses are
semantically minimal and each consist of a set of disjuncts. These disjuncts
are each independent explanations, and are not redundant with respect to the
background ontology or the other disjuncts, representing a form of hypothesis
space. The observations and hypotheses handled by the method can contain both
atomic or complex ALC concepts, excluding role assertions, and are not
restricted to Horn clauses. Two approaches to redundancy elimination are
explored for practical use: full and approximate. Using a prototype
implementation, experiments were performed over a corpus of real world
ontologies to investigate the practicality of both approaches across several
settings.
