@TECHREPORT{Orgun95atemporal, author = {Mehmet Al I Orgun}, title = {A Temporal Algebra with Recursive Equations}, institution = {}, year = {1995} }

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Abstract

This paper introduces a recursive temporal algebra for querying time-varying data. The algebra, called ! , is based on a temporal relational data model in which a temporal database is modeled as a collection of time-varying relations. Each time-varying relation is a collection of ordinary relations indexed by moments in time. In ! , recursive queries (such as the transitive closure of a given relation) can be formulated through equations. It is shown that other forms of recursion, such as linear recursion, can also be expressed using iteration through time. The meaning of recursive equations is formulated using a standard approach based on fixed-point semantics. Temporal completeness of ! with bounded time is established, with respect to two other temporal algebras based on temporal semantics which also offer linear recursive operators. Keywords: Temporal databases, temporal algebras, time-varying relations, recursive queries, recursive equations, fixed-point semantics, linea...