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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)
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)
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)
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)