Which of the following well-formed formula(s) are valid?
A.((P → Q)^(Q → R))→ (P → R)
B.(P → Q) →(˥P → ˥Q)
C.(P v (˥P v ˥Q)) →P
D.((P → R) v (Q → R)) → (P v Q}→R)
Answer:A
Which of the following well-formed formula(s) are valid?
A.((P → Q)^(Q → R))→ (P → R) B.(P → Q) →(˥P → ˥Q) C.(P v (˥P v ˥Q)) →P D.((P → R) v (Q → R)) → (P v Q}→R)