Description

HOMEWORK 1
(1) Show p =⇒ q,r =⇒ s ` p ∧ r =⇒ q ∧ s is valid.
(2) Show (p ∧ q) ∨ (p ∧ r) ` p ∧ (q ∨ r) is valid.
(3) Show p ∧ q =⇒ r ` (p =⇒ r) ∨ (q =⇒ r) is valid.
(4) Show p =⇒ q `¬p ∨ q is valid.
(5) Show ` (p =⇒ q) ∨ (q =⇒ r) is valid.
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