Date Added: Jun 2011
This paper is about query rewriting in the context of ontological database access. Query rewriting is an important new optimization technique specific to ontological queries. The essence of query rewriting, as will be explained in more detail below, is to compile a query and an ontological theory (usually formulated in some description logic or rule-based language) into a target query language that can be directly executed over a relational DataBase Management System (DBMS). The advantage of such an approach is obvious. Query rewriting can be used as a pre-processing step for enabling the exploitation of mature and efficient existing database technology to answer ontological queries.