Distributed Resolution for ALC - First Results

The use of description logic as the basis for semantic web languages has led to new requirements with respect to scalable and non-standard reasoning. Description logic is a decidable fragment of FOL but still, the standard reasoning tasks are of exponential complexity, satisfiability and subsumption tests are often intractable on large ontologies. Existing large ontologies have a modular structure like networks of linked ontologies, caused by the development process. However, current reasoning approaches do scarcely take advantage of this structure. The available reasoners do not exploit parallel computation and scalability improvements enabled by distributed reasoning. In this paper, we lay the foundation for developing distributed reasoning methods by showing that the description logic fragment ALC can be distributed. We propose a distributed, complete and terminating algorithm that decides satisfiability of terminologies in ALC. The algorithm is based on recent results on applying resolution to description logics. We show that the resolution procedure proposed by Tammet can be distributed amongst multiple resolution solvers by assigning unique sets of literals to individual solvers. This provides the basis for a highly scalable reasoning infrastructure for description logics.