Joshua Taylor Discovering Simple Mappings Gregory Todd Williams 1

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• Question is for the Presentation: Joshua Taylor presents Discovering Simple Mappings Between Relational Database Schemas and Ontologies
• Question is asked by: Gregory Todd Williams
• The Question is: The definition of a mapping (Definition 3) is stated in such a way as to allow mappings from R to P and from A to C. Is this just a sloppy definition? In figure 1 just below definition 3, a mapping from "Paper" in R to "Journal Paper" in O is shown with "Paper" subsuming "Journal Paper". Of what use is this mapping given the stated direction of subsumption? If the relation subsumes the class, aren't we unable to say anything about the class that a tuple in the relation belongs to?
• Question is answered by: Joshua Taylor
• The Answer is: The definition may be a bit sloppy — 4.1 Classifying Entity Types restricts the simple mappings that will actually be considered: (database) relations to (ontology) classes or object properties; (database) attributes to (ontology) datatype or object properties. The mapping space of Definition 3, then, is a superset of the simple mappings considered in this paper. The subsumption mapping between Paper and Journal Paper is useful even if it does not immediately help place an individual described by a row in the table into a class in the ontology, because it can later help in consistency checking, for example, in domain and range checking.