Theorem 2a1

Description: A double form of ax-1 . Its associated inference is 2a1i . Its associated deduction is 2a1d . (Contributed by BJ, 10-Aug-2020) (Proof shortened by Wolf Lammen, 1-Sep-2020)

	Ref	Expression
Assertion	2a1	$$⊢\phi \to \left(\psi \to \left(\chi \to \phi \right)\right)$$

Proof

Step	Hyp	Ref	Expression
1		id	$$⊢\phi \to \phi$$
2	1	2a1d	$$⊢\phi \to \left(\psi \to \left(\chi \to \phi \right)\right)$$