A fuzzy set-based approach to temporal databases

The primary aim of temporal databases is to offer a common framework to those DB applications that need to store or handle different types of temporal data from a variety of sources since they allow the concept of time to be unified from the point of view of meaning, representation and manipulation. Although at first sight the incorporation of time into a DB might appear to be a direct and even simple task, it is, however, quite complex because not only must new structures and specific operators be included but the semantics of classical manipulation sentences (insert, update or delete) must be changed when temporal data are present. In addition, temporal information is not always as precise as desired since it is affected by imprecision due to the use of natural language or to the nature of the source. In this paper, we deal with the problem of the update and query operations when time is expressed by means of a fuzzy interval of dates. Throughout the text, we will see how the delete and insert operations are particular cases of the update process and will therefore be implicitly presented in the paper.