NOTE ON THE SET ABSTRACTION IN LOGIC PROGRAMMING LANGUAGE.

The concept of set abstraction is introduced as a simple analogy to lambda abstraction in the theory of lambda calculus. The set abstraction is concerned with two extensions of language features: set expression and predicate variable. Combining these two concepts of extensions to Prolog, we define set abstraction as the set expression in which predicate variables are allowed as data objects. In other words, the set abstraction gets involved in the higher order predicate logic. It is demonstrated that with the help of predicate variables, set abstractions can nicely handle the world of the second order predicate logic. Implementation programs written in Prolog and Concurrent Prolog are presented.