Metamath Proof Explorer


Theorem nfae

Description: All variables are effectively bound in an identical variable specifier. Usage of this theorem is discouraged because it depends on ax-13 . (Contributed by Mario Carneiro, 11-Aug-2016) (New usage is discouraged.)

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

Proof

Step Hyp Ref Expression
1 hbae
 |-  ( A. x x = y -> A. z A. x x = y )
2 1 nf5i
 |-  F/ z A. x x = y