80-211 Spring 2003
Due on Wednesday, April 23rd
Problem 1: Do problems 2 and 3 on pages 187-8 of your text.
Problem 2: Given any two relations S and T, one defines a new relation T○S, called the composite (or relational product) of S and T by:
(T○S)xy =df ($z)(Sxz & Tzy)
A relation R is said to be functional if it satisfies the conditions:
(i) (x)( $y) Rxy
(ii) (x)(y)(z) [(Rxy & Rxz) ® (y=z)]
Using predicate calculus with equality, show that the composite of two functional relations is again functional.