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Information systems: On queries involving cardinalities

Authors
Journal
Information Systems
0306-4379
Publisher
Elsevier
Publication Date
Volume
4
Issue
3
Identifiers
DOI: 10.1016/0306-4379(79)90008-5
Disciplines
  • Linguistics
  • Mathematics

Abstract

Abstract A query language is considered allowing queries which ask for the cardinality of a set of objects satisfying specified conditions, or ask whether or not some relations (equalities, inequalities, etc.) hold between the cardinalities of sets of objects satisfying some conditions. We describe a precise semantics of this language, and we give a complete axiom system for equivalent transformations of queries. By using these axioms we are able to transform any query into a normal form which makes the retrieval process more efficient.

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