Introduction
Though the problem of integrating heterogeneous relational databases has been
studied extensively, it remains a fact that integration of data at the semantic
level remains an open problem.
In this work, we provide a graphbased simple definition of an ontology and propose
the notion of an ontology extended relation (OER). An OER contains an ordinary
relation as well as an associated ontology that conveys semantic meaning about
the terms being used. In order to answer queries spanning multiple OERs, we study the problem of integrating ontologies under a given set
of interoperation constraints. We formally define the notion of canonical witness to the integrability of a set of ontologies under such constraints. We have established
a theory that a set S of ontologies is integrable if and only if the canonical witness is
a witness to the integrability of the ontologies in S. We further provide an efficient algorithm
to compute the canonical witness given a set of ontologies and their interoperation constraints.
Then we extend the relational algebra to query such OERs.
We have built a prototype system called HOME to implement the OER
model and the ontologyextended relational algebra. By using the US geological survey data as
a testbed, we experimentally show that our HOME system scales well to handle large data sets.
People
Piero Bonatti, Yu Deng, V.S. Subrahmanian, T.J. Rogers,
Jeremy Hoffman, Vincenzo Vecchio
Publications
 Piero Bonatti, Yu Deng and V.S. Subrahmanian. An OntologyExtended Relational Algebra. In Proceedings of the
IEEE International Conference on Information Reuse and Integration
(IEEE IRI 2003), Las Vegas, USA, October 2729, 2003.
Presentations
 Yu Deng,
"An OntologyExtended Relational Algebra," the
IEEE International Conference on Information Reuse and Integration
(IEEE IRI 2003), October 2003. (powerpoint)
