Given the propositional statement: (~q ⋀ (p→q))→~p, which of the following…
Given the propositional statement: (~q ⋀ (p→q))→~p, which of the following options is correct about it?
Answer: B. Tautology — To determine the nature of the propositional statement (~q ⋀ (p→q))→~p, we simplify it using logical equivalences. Step 1: Rewrite the implication p→q as ~p ⋁…
- A.
Contingency
- B.
Tautology
- C.
Contradiction
- D.
Invalid
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Correct answer: B
To determine the nature of the propositional statement (~q ⋀ (p→q))→~p, we simplify it using logical equivalences.
Step 1: Rewrite the implication p→q as ~p ⋁ q.
So, (~q ⋀ (p→q))→~p becomes (~q ⋀ (~p ⋁ q))→~p.
Step 2: Apply distributive law: ~q ⋀ (~p ⋁ q) ≡ (~q ⋀ ~p) ⋁ (~q ⋀ q).
Since ~q ⋀ q is a contradiction (always false), the expression simplifies to (~q ⋀ ~p).
So, the original statement becomes (~q ⋀ ~p)→~p.
Step 3: Rewrite the implication: (~q ⋀ ~p)→~p ≡ ~(~q ⋀ ~p) ⋁ ~p.
Apply De Morgan's law: ~(~q ⋀ ~p) ≡ q ⋁ p.
So, the expression becomes (q ⋁ p) ⋁ ~p.
Step 4: Simplify using associativity and complement law: p ⋁ ~p ≡ 1.
Thus, (q ⋁ p) ⋁ ~p ≡ q ⋁ (p ⋁ ~p) ≡ q ⋁ 1 ≡ 1.
Since the expression simplifies to 1 (true) for all truth values of p and q, it is a tautology.