On time-invariance and synchronism in valid-time relational databases
Jef Wijsen, Jacques Vandenbulcke, Hendrik Olivié · 1994
. We propose new temporal dependencies for valid-time relations. The proposed dependencies can be thought of as generalizations of the temporal database concept of time-invariant attribute. They are natural extensions of the conventional construct of functional dependency. A complete axiomatization is obtained by extending Armstrong's axioms. The new dependencies can be expressed in a first-order temporal predicate calculus with equality. We argue that temporal dependency preservation may constitute a valuable design guide-line during normalization. Keywords. temporal databases, relational data model, functional dependency, temporal logic 1. Reserach Assistant of the National Fund for Scientific Research (Belgium). 1193 1. Introduction Temporal database constraints, in general, can be expressed as formulas of temporal logic that must be satisfied by any "legal" database. Several temporal logics can be found in literature [1,4,8,14]. Certain temporal constraints are more significan...