Querying and Updating Constraint Databases with Incomplete Information

It is the aim of the research described in this paper is to to extend the work to deductive databases by proposing a theory of indefinite deductive constraint databases (IDCDs). This model provides a useful and natural representation of partial and infinite information. As a result of basing our representation of incomplete information on constraints, we can easily extend our model in order to enable the representation of temporal and/or spatial data by defining the domain of variables over which constraints can be defined to either be the temporal or spatial domain or by using, for example, linear arithmetic constraints to represent these domains. We describe how the syntax of the deductive database model can be enhanced with global conditions on incompletely specified constants to naturally represent partial information and provide a full declarative, fixpoint and procedural semantics for the language defined. We discuss an as yet unexplored problem with respect to constraint databases - that of updating and maintaining a consistent set of data in the presense of global conditions on incomplete information.