Uniformly Querying Knowledge Bases and Data Bases

Present kl-one-like knowledge base management systems (KBMS), whilst ooer-ing highly structured description languages aside eecient concepts classiication, have limited capability to manage large amounts of individuals. Data base management systems (DBMS) can, instead, manage large amounts of data eeciently, but give scarce formalism to organize them in a structured way, and to reason with them. This paper shows how assertional knowledge of KBMS and data of DBMS can be uniformly accessed. The query answering capability of an arbitrary KBMS is augmented with the possibility of accessing external databases (DB) as a supplemental source of extensional knowledge. The techniques presented in this paper can be easily adapted to several sources of information. From a knowledge acquisition perspective, we believe that they can be usefully applied in all those applications where several sources of informations are available independently from the knowledge bases.