Relational Conditional Set Operations

Abstract

A set is a collection of different objects. Some basic operations from the Theory of Sets are the set membership (∈ ), subset (⊂ ), intersection (∩ ), and difference (−). However, these operations have limitations because of the implicit use of the identity predicate. That is, a tuple is a member of a set if it is identical to any tuple in the set. Many applications need other comparison predicates that are not limited to identity. This paper presents the new Relational Conditional Set Operations, or RelCond Set Operations (∈ c, ⊆ c, ∩ c, - c ) for short. Our operators are naturally suited to answer queries of conditional membership, subset, intersection, and difference with customized predicates. For example, they are potentially useful in applications of product sales with units and prices, job promotion, and internship. We validate our proposals by studying the first of these applications.