Temporal Logic in Information Systems

Temporal logic is obtained by adding temporal connectives to a logic language. Explicit references to time are hidden inside the temporal connectives. Di erent variants of temporal logic use di erent sets of such connectives. In this chapter, we survey the fundamental varieties of temporal logic and describe their applications in information systems. Several features of temporal logic make it especially attractive as a query and integrity constraint language for temporal databases. First, because the references to time are hidden, queries and integrity constraints are formulated in an abstract, representationindependent way. Second, temporal logic is amenable to e cient implementation. Temporal logic queries can be translated to an algebraic language. Temporal logic constraints can be e ciently enforced using auxiliary stored information. More general languages, with explicit references to time, do not share these properties. Recent research has proposed various implementation techniques to make temporal logic practically useful in database applications. Also, the relationships between di erent varieties of temporal logic and between temporal logic and other temporal languages have been clari ed. We report on these developments and outline some of the remaining open research problems. v