Temporal Relational Calculus

Synonyms

Two-sorted first-order logic

Definition

Temporal Relational Calculus (TRC) is a temporal query language extending the relational calculus. In addition to data variables and quantifiers ranging over a data domain (a universe of uninterpreted constants), temporal relational calculus allows temporal variables and quantifiers ranging over an appropriate time domain [1].

Key Points

A natural temporal extension of the relational calculus allows explicit variables and quantification over a given time domain, in addition to the variables and quantifiers over a data domain of uninterpreted constants. The language is simply the two-sorted version (variables and constants are temporal or non-temporal) of first-order logic over a data domain D and a time domain T.

The syntax of the two-sorted first-order language over a database schema ρ ={R ₁,...,R _k } is defined by the grammar rule:

$$\eqalign{Q ::= & R({t}_{i},{x}_{{i}_{1}},{ ...},{x}_{{i}_{k}})\vert {t}_{i} < {t}_{j}\vert {x}_{i} =...