General Indefinite and Maybe Information in Relational Databases

This paper generalizes the relational model to represent indefinite and maybe kinds of incomplete information. A data structure, called M-table, is introduced which is capable of representing disjunctive/indefinite and maybe facts. The notion of redundancy in the context of indefinite and maybe information is studied. The relational algebra is generalized in a semantically correct manner to operate on M-tables. Two additional operators, R-projection and merge, are introduced. Queries are posed in the same manner as in the conventional algebra, however the user may now expect indefinite as well as maybe answers.