Theorem 3mix2i

Description: Introduction in triple disjunction. (Contributed by Mario Carneiro, 6-Oct-2014)

	Ref	Expression
Hypothesis	3mixi.1	$$⊢\phi$$
Assertion	3mix2i	$$⊢\left(\psi \vee \phi \vee \chi \right)$$

Proof

Step	Hyp	Ref	Expression
1		3mixi.1	$$⊢\phi$$
2		3mix2	$$⊢\phi \to \left(\psi \vee \phi \vee \chi \right)$$
3	1 2	ax-mp	$$⊢\left(\psi \vee \phi \vee \chi \right)$$