DFL - A dialog based integration of concept and rule reasoners

Description logics (DLs) are subsets of first-order logic (FOL), designed for reasoning about class-based knowledge. Their expressive power is deliberately restricted, so as to enable efficient inference. A DL reasoner or knowledge base is intended to be embedded as a special purpose component in a heterogeneous knowledge base. Therefore, the development of integration frameworks of DLs and other forms of reasoning is essentially important. In this paper, we introduce a formal scheme for the integration of information sources for which a combined declarative semantics is not available. The integration is defined by a syntactic compositional semantics, and implemented by a dialog process in which the independent reasoners make their failures public. This scheme is used to formalize the integration of a DL reasoner with an expressive rule reasoner (for which a combined declarative semantics is not known). It is implemented in the DFL system, that integrates a DL reasoner and an F-Logic rule reasoner. The integrated system gives rise to a rich dialog between its components, since the DL inferences can trigger new rule inferences, and rule inferences can trigger new DL inferences. The DFL system is the first to support a true dialog between a DL and a rule reasoners, that operate under different semantical policies, e.g., the open world assumption (OWA) for the DL reasoner, and the closed world assumption (CWA) for the rule reasoner. This architecture generalizes all existing hybrids of descriptions and rules.