Metamath Proof Explorer


Theorem nfnae

Description: All variables are effectively bound in a distinct variable specifier. Usage of this theorem is discouraged because it depends on ax-13 . Use the weaker nfnaew when possible. (Contributed by Mario Carneiro, 11-Aug-2016) (New usage is discouraged.)

Ref Expression
Assertion nfnae
|- F/ z -. A. x x = y

Proof

Step Hyp Ref Expression
1 nfae
 |-  F/ z A. x x = y
2 1 nfn
 |-  F/ z -. A. x x = y