Chapter 11 Problem 055 A proposed project has the following
Solution
We will consider the possible cases where they are not equivalent. (1) Suppose p $ q is true while ¬(p 2 q) is false. For p $ q to be true, p and q have to both be true or both be false. (a) If both are true, then (p 2 q) will be false, and ¬(p 2 q) will be true, contradicting our assumption that ¬(p 2 q) is false. Thus this case is not possible. (b) If both are false, then (p 2 q) will be false, and ¬(p 2 q) will be true, again contradicting our assumption that ¬(p 2 q) is false. Thus this case is not possible. (2) Suppose p $ q is false while ¬(p 2 q) is true. Then for p $ q to be false, p and q have dierent truth values. (a) Assume p is true and q is false. Then (p2q) is true so ¬(p2q) is false, contradicting our assumption that ¬(p 2 q) is true. Thus this case is not possible
