EXTENSION OF THE RELATIONAL DATABASE AND ITS ALGEBRA WITH ROUGH SET TECHNIQUES

This paper describes a database model based on the original rough sets theory. Its rough relations permit the representation of a rough set of tuples not definable in terms of the elementary classes, except thr ough use of lower and upper approximations. The rough relational datab ase model also incorporates indiscernibility in the representation and in all the operators of the rough relational algebra. This indiscerni bility is based strictly on equivalence classes which must be defined for every attribute domain. There are several obvious applications for which the rough relational database model can more accurately model a n enterprise than does the standard relational model. These include sy stems involving ambiguous, imprecise, or uncertain data. Retrieval ove r mismatched domains caused by the merging of one or more applications can be facilitated by the use of indiscernibility, and naive system u sers can achieve greater recall with the rough relational database. In addition, applications inherently ''rough'' could be more easily impl emented and maintained in the rough relational database.