CIS 125

13– Direct Proof

Note: The tilde (~) is used to denote a logical inversion, or NOT, operation.

The symbol v is used to represent the OR operator, while the ^ symbol represents the AND operator.

For problems 1-5, use truth tables to determine whether each argument is valid.

1. p r

p q

------------

p (r ^ q)

2. p (r v q)

r ~q

------------

p r

3. p r

r q

------------

q

4. ~r ~p

r

------------

p

5. p r

r q

p

------------

q