Theorem axc16

Description: Proof of older axiom ax-c16 . (Contributed by NM, 8-Nov-2006) (Revised by NM, 22-Sep-2017)

	Ref	Expression
Assertion	axc16	$$⊢\forall xx=y\to \left(\phi \to \forall x\phi \right)$$

Proof

Step	Hyp	Ref	Expression
1		axc16g	$$⊢\forall xx=y\to \left(\phi \to \forall x\phi \right)$$