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- Marc Gyssens, Jan Paredaens, Dirk Van Gucht
- PODS
- 1990

A simple, graph-oriented database model, supporting object-identity, is presented. For this model, a transformation language based on elementary graph operations is defined. This transformation language is suitable for both querying and updates. It is shown that the transformation language supports both set-operations (except for the powerset operator) and… (More)

- Marc Gyssens, Jan Van den Bussche, Dirk Van Gucht
- J. Comput. Syst. Sci.
- 1999

We extend Chandra and Harel's seminal work on computable queries for re-lational databases to a setting in which also spatial data may bepresent, using a constraint-based data model. Concretely, we introduce bothcoordinate-based and point-based query languages that are complete in the sense that they can express precisely all computable queries that are… (More)

- Jung-Yul Suh, Dirk Van Gucht
- ICGA
- 1987

- Marc Gyssens, Jan Paredaens, Dirk Van Gucht
- SIGMOD Conference
- 1990

- Jan Paredaens, Dirk Van Gucht
- PODS
- 1988

- Jan Paredaens, Paul De Bra, Marc Gyssens, Dirk Van Gucht
- EATCS Monographs on Theoretical Computer Science
- 1989

- Jan Paredaens, Jan Van den Bussche, Dirk Van Gucht
- SIAM J. Comput.
- 1995

We investigate properties of finite relational structures over the reals expressed by first-order sentences whose predicates are the relations of the structure plus arbitrary polynomial inequalities, and whose quantifiers can range over the whole set of reals. In constraint programming terminology, this corresponds to Boolean real polynomial constraint… (More)

- Marc Gyssens, Dirk Van Gucht
- SIGMOD Conference
- 1988

In this paper, we discuss augmentations of the nested relational algebra with programming constructs, such as while-loops and for-loops. We show that the algebras obtained in this way are equivalent to a slight extension of the powerset algebra, thus emphasizing both the strength and the naturalness of the powerset algebra as a tool to manipulate nested… (More)

- Paul W. Purdom, Dirk Van Gucht, Dennis P. Groth
- SIAM J. Comput.
- 2004

The Apriori Algorithm examines baskets of items to determine which subsets of the items occur in lots of baskets. Suppose we wish to determine which items sets occur in at least k baskets. The algorithm considers item sets of size l in the order l = 1, 2, : : :. The only way this algorithm can determine that a set occurs at least k times is to count the k… (More)