An Extended Relational Algebra on Abstract Objects for Summarizing Answers to Queries

Article type: Research Article

Authors: Demolombe, Robert

Affiliations: 2 Avenue E. Belin, 31055 Toulouse Cedex 4, France

Abstract: Answers to queries in terms of abstract objects are defined in the logical framework of first order predicate calculus. A partial algebraic characterisation of the supremum and of the infimum of abstract answers is given in an extended Relational Algebra of the Cylindric Algebra kind. Then, the form of queries is restricted in order to be able to compute answers without the cylindrification operator. For these restricted queries we give a technique to compute an upper bound and a lower bound of abstract answers using only the operators of the standard Relational Algebra.

Keywords: relational algebra, cylindric algebra, first order logic, abstraction

Journal: Fundamenta Informaticae, vol. 57, no. 1, pp. 1-15, 2003