About the projection operator in a possibilistic database framework

This paper deals with databases containing ill-known attribute values represented by possibility distributions. In order to manipulate such databases in a safe and efficient way, a constrained framework has been previously suggested, where a restricted number of querying operations are permitted (selections and foreign key joins calling on attributes taking imprecise values). The key for efficiency resides on the fact that these operators do not require to make computations explicitly over all the more or less possible worlds. An extension of this model involving the projection operator is proposed in this paper.