CSC165H1F Tutorial # 4 Fall 2011
1. Write detailed proof structures for each of the following statements. Don’t write complete proofs|for
now, focus on the proof structure only and leave out all of the actual \content".
(a) 8x 2 Z;8y 2 Z;x 6 y ) 9z 2 Z;x 6 z 6 y
(b) 8x 2 Z;(9y 2 Z;x = 3y + 1) ) (9y 2 Z;x = 3y + 1)
(c) :8x 2 N;9y 2 N;y > x ^ a >ya x
Dept. of Computer Science, University of Toronto, St. George Campus Pa