Publication
POPL 1975
Conference paper

An algebra of relations for machine computation

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Abstract

This paper extends the relational algebra of data bases, presented bv Codd [41 and others, in four areas. The first is the use of selector names to remove order dependencies from the columns of a relation. This use of selector names enables us to define a more general class of operations, which include the normal relational operations of union, equi-join etc., as special cases. Thirdly we introduce relations represented algorithmically as well as by a stored set of tuples. Such computed relations cannot always be effectively realised as a finite set of tuples. Finally we consider relational expressions as algorithmic representations of relations and characterize their effectiveness.

Date

20 Jan 1975

Publication

POPL 1975

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