On the specification of representation-based conditions in a context of incomplete databases

Abstract

In this paper, we are concerned with the querying of databases containing imperfect attribute values. In the usual querying approach, a condition compares a variable (associated with an attribute) and a value, which leads to an answer pervaded with uncertainty. In the approach we propose (described as representation-based), a condition concerns the representation of an ill-known attribute value, and, as such, induces no uncertainty in the answers. The idea is to exploit at the querying level some concepts which are part of the model used for representing ill-known data, and which concern the qualification of imprecision/uncertainty. A formal framework suited to the expression of this new type of query is presented and a typology of representation-based queries is given, with the corresponding expressions in that framework.