Relational databases with exclusive disjunctions

The author presents a mechanism for representing exclusive disjunctive information in database tables using various tuple types and a range for the count of the number of tuples in the unknown relation denoted by a table. The relational algebra operators are extended to take the new tables as operands. Query evaluation in the extended model is sound and complete for relational algebra expressions consisting of projection, difference, Cartesian product, or selection operators. Possible storage structures for storing the base tables and algorithms for inserting tuples into a table are described