Theorem a1i

Description: Inference introducing an antecedent. Inference associated with ax-1 . Its associated inference is a1ii . See conventions for a definition of "associated inference". (Contributed by NM, 29-Dec-1992)

	Ref	Expression
Hypothesis	a1i.1	$$⊢\phi$$
Assertion	a1i	$$⊢\psi \to \phi$$

Proof

Step	Hyp	Ref	Expression
1		a1i.1	$$⊢\phi$$
2		ax-1	$$⊢\phi \to \left(\psi \to \phi \right)$$
3	1 2	ax-mp	$$⊢\psi \to \phi$$