A logical reconstruction of temporal databases

Traditional approaches to temporal databases are either not formal or deal only with static features, considering mainly a single state of the database. The temporal nature of data in temporal databases, however, is intrinsically dynamic, for it deals with the evolution of data. In this work, a temporal logic framework is proposed to simultaneously cope with both the static and the dynamic aspects of temporal data. The framework consists of a two-dimensional temporal model. One-dimensional temporal models deal with static aspects such as temporal querying and data representation. The second temporal dimension is introduced as a natural extension that captures the dynamics of temporal updates. The resulting twodimensional temporal model is used to formally characterize the differences between valid time and transaction time, to characterize the notion of ‘now’ in a temporal database, and to give a formal model for bitemporal databases.