Exercise logic.propositional.consequence
Description
Prove that formula is a logical consequence of a set of formulas
Derivation
![](http://ideas.cs.uu.nl/images/external.png)
(p || q) /\ (p || r) => ~~p || r
⇒ logic.propositional.notnot(p || q) /\ (p || r) => p || r
⇒ conj-elimp || r => p || r