Exercise logic.propositional.consequence

Description
Prove that formula is a logical consequence of a set of formulas

Derivation

(p || q) /\ (p || r) => ~p -> r

⇒ logic.propositional.defimpl

(p || q) /\ (p || r) => ~~p || r

⇒ logic.propositional.notnot

(p || q) /\ (p || r) => p || r

⇒ conj-elim

p || r => p || r