document: On directly mapping relational databases to RDF and OWL Mapping relational databases to RDF is a fundamental problem for the development of the Semantic Web . We present a solution , inspired by draft methods defined by the W3C where relational databases are directly mapped to RDF and OWL . Given a relational database schema and its integrity constraints , this direct mapping produces an OWL ontology , which , provides the basis for generating RDF instances . The semantics of this mapping is defined using Datalog . Two fundamental properties are information preservation and query preservation . We prove that our mapping satisfies both conditions , even for relational databases that contain null values . We also consider two desirable properties : monotonicity and semantics preservation . We prove that our mapping is monotone and also prove that no monotone mapping , including ours , is semantic preserving . We realize that monotonicity is an obstacle for semantic preservation and thus present a non-monotone direct mapping that is semantics preserving .
doc_bio_tags: O O O B I O B O B O B I O B O O O O O O O O O B I O O O O O O O O O O O O O O O B I O O O O B O B O O O O O O O O O O O O B I O O B O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O