Theorem exmidd

Description: Law of excluded middle in a context. (Contributed by Mario Carneiro, 9-Feb-2017)

	Ref	Expression
Assertion	exmidd	$$⊢\phi \to \left(\psi \vee \neg \psi \right)$$

Proof

Step	Hyp	Ref	Expression
1		exmid	$$⊢\left(\psi \vee \neg \psi \right)$$
2	1	a1i	$$⊢\phi \to \left(\psi \vee \neg \psi \right)$$