Theorem vd02

Description: Two virtual hypotheses virtually infer a theorem. (Contributed by Alan Sare, 14-Jun-2011) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypothesis	vd02.1	$$⊢\phi$$
Assertion	vd02	$$⊢\left(\psi ,\chi \to \phi \right)$$

Proof

Step	Hyp	Ref	Expression
1		vd02.1	$$⊢\phi$$
2	1	a1i	$$⊢\chi \to \phi$$
3	2	a1i	$$⊢\psi \to \left(\chi \to \phi \right)$$
4	3	dfvd2ir	$$⊢\left(\psi ,\chi \to \phi \right)$$