Projects          People          Publications          Presentations          Videos          Contact
Semantics and Integration
   Probabilistic ontologies

   Annotated RDF



Ontology systems

   RDF views



Related projects and labs



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 graph-based 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 ontology-extended 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.


Piero Bonatti, Yu Deng, V.S. Subrahmanian, T.J. Rogers, Jeremy Hoffman, Vincenzo Vecchio


  • Piero Bonatti, Yu Deng and V.S. Subrahmanian. An Ontology-Extended Relational Algebra. In Proceedings of the IEEE International Conference on Information Reuse and Integration (IEEE IRI 2003), Las Vegas, USA, October 27-29, 2003.


  • Yu Deng, "An Ontology-Extended Relational Algebra," the IEEE International Conference on Information Reuse and Integration (IEEE IRI 2003), October 2003. (powerpoint)
Last updated: March 26 2008
Contact us with questions or comments