Graph-based Data Models

Our work in graph-based data models was initially motivated by the desire to design visual methods of representing, querying, and updating complex data sets. The challenge is to balance visual effectiveness with representational and computational expressiveness. We developed a graph-based data model called the Hypernode Model which is based on nested graphs termed hypernodes. Arbitrarily complex objects can be represented by a network of hypernodes. We developed a language for browsing, querying and updating hypernode databases, called Hyperlog. Subsequent work has been in techniques for visualisation, navigation and querying of web information, including most recently work on flexible query processing for RDF.


Hyperlog: a graph-based system for database browsing, querying and update (abstract). A.Poulovassilis and S.Hild. IEEE Knowledge and Data Engineering, 13(2), pp 316-333, 2001.

An Architecture for Web Visualisation Systems. P.Demetriades and A.Poulovassilis. Presented at the Workshop on Reuse of Web Information, held in conjunction with WWW'98, Brisbane, April 1998.

Implementing Hyperlog, a Graphical Database Query and Update Language (abstract). S.Hild and A.Poulovassilis. Journal of Visual Languages and Computing, Vol. 7, pp 267-289, July 1996.

Hyperlog: a system for database querying and browsing (abstract). S.Hild and A.Poulovassilis. Proc. of the 1996 International Workshop in Advanced Visual Interfaces (AVI'96), Gubbio, Italy, pp 260-262, May 1996.

A Nested-Graph Model for the Representation and Manipulation of Complex Objects (abstract). A.Poulovassilis and M.Levene. ACM Trans. on Information Systems, Vol. 12, No. 1, pp 35-68 1994.

Implementation of a Graph-Based Data Model for Complex Objects (abstract). M.Levene, A.Poulovassilis, K.Benkerimi, S.Schwartz and E.Tuv. ACM SIGMOD Record, Vol. 22, No. 4, pp 26-31, 1993.

Semi-Naive Evaluation for Hyperlog, a Graph-Based Language for Complex Objects (abstract). K.Benkerimi and A.Poulovassilis. Proc. 1st International Workshop on Rules in Databases, Edinburgh, August 1993, pp 251-267. Springer-Verlag Workshops in Computer Science.

A Storage Manager for the Hypernode Model (abstract). E.Tuv, A.Poulovassilis and M.Levene. Proc. 10th British National Conference on Databases, Aberdeen, July 1992, pp 59-77. Lecture Notes in Computer Science 618, Springer-Verlag.

An Object-Oriented Data Model Formalised Through Hypergraphs (abstract). M.Levene and A.Poulovassilis. Data and Knowledge Engineering, Vol. 6, pp 205-224, 1991. North Holland.

The Hypernode Model as the basis for a CASE Information Repository (abstract). M.Levene, A.Poulovassilis and R.Offen. Proc. 4th International Workshop on Computer-Aided Software Engineering, Irvine Ca., December 1990, pp 216-218. IEEE Computer Society Press.