Multiple Inheritance and the Closure of Set Operators in Class Hierarchies

Abstract

In this report, we establish essential closures in class hierarchies of database systems that support set operations, such as union and intersection, in their query language. In particular, we rigorously demonstrate that multiple inheritance is an implementation requirement, as is the formal treatment of the class hierarchies as lattices with defined least upper, and greatest lower, bound operators. Note: Abstract extracted from PDF file via OCR