Ch 4 Quantifiers, negation and proof techniques

Question 1

Formula for negating a statement

Answer 1

Change all ‘for all’ symbols with ‘there exists’ and vice versa. Change s.t A to s.t not A

Question 2

How to prove one statement is a negation of the other

Answer 2

They will have opposite truth tables

Question 3

Proof techniques

Answer 3

Indirect proof
Contrapositive proof (to prove if A then B, instead prove if not B then not A)

Question 4

Negation of ‘A implies B’

Answer 4

A and not B

Question 5

Going from infinite unions and intersections to sets general rule

Answer 5

Unions give an interval, intersections give numbers