From the premises ¬¬P ∨ Q, P ↔ R, and H → ¬Q derive H → P using the inference rules and equivalence lawsfrom the lectures. Start with the premises and state in each step which rule you are using. Following from this, Let¬¬P ∨ Q be true and H → ¬Q be true. Prove that H → P is true by contradiction.
Question
From the premises ¬¬P ∨ Q, P ↔ R, and H → ¬Q derive H → P using the inference rules and equivalence lawsfrom the lectures. Start with the premises and state in each step which rule you are using. Following from this, Let¬¬P ∨ Q be true and H → ¬Q be true. Prove that H → P is true by contradiction.
Solution
Step 1: Start with the premises ¬¬P ∨ Q (Premise 1) P ↔ R (Premise 2) H → ¬Q (Premise 3)
Step 2: Apply Double Negation to Premise 1 P ∨ Q (Double Negation)
Step 3: Apply Modus Tollens to Premise 3 and Step 2 If H is true, then ¬Q is true (from Premise 3). If Q is true, then P is true (from Step 2). Therefore, if H is true, then P is true. H → P (Modus Tollens)
Now, let's prove H → P by contradiction:
Step 4: Assume the opposite of what we want to prove Assume ¬(H → P) is true. This means that H is true and P is false.
Step 5: Apply Modus Tollens to Premise 2 and our assumption If P is false, then R is false (from Premise 2). But we assumed that H is true, which contradicts our assumption that P is false. Contradiction
Therefore, our assumption that ¬(H → P) is true must be false. Hence, H → P is true.
Similar Questions
1. Show that the following argument with hypotheses on lines 1-2 and conclusion on line c is valid using the rules of inference and logical equivalences. Clearly label each step. 1 p → q Premise 2 (r ∨ s) → (p ∧ ¬q) Premise . . . c ¬r Conclusion
Assume that all of the following are true(P ∨ Q) ⇒ RQ ∨ RR ⇒ PShow by contradiction that P is true.3
p → q is logically equivalent to ¬p ∧ q¬p ∨ q¬p ∨ ¬qp ∨ ¬q
Using laws of logic prove that following are equivalenti)~ ( ) and ~ p q p q →
State whether each of the following propositions is a tautology or a contradiction or contingent (i.e. neither).You must give a (brief) reason to justify each of your answers.(a) P(b) (P ∧ Q) → (P → Q)(c) ¬(P → Q) → (¬Q)(d) (¬Q ∧ (P → Q)) → ¬P(e) ((P → Q) ∧ (Q → R)) ↔ (P → R)(f) (R ∨ P ) → (P ∨ (Q ∨ R))
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.