Theorem sbequ6

Description: Substitution does not change a distinctor. Usage of this theorem is discouraged because it depends on ax-13 . (Contributed by NM, 5-Aug-1993) (New usage is discouraged.)

	Ref	Expression
Assertion	sbequ6	|- ( [ w / z ] -. A. x x = y <-> -. A. x x = y )

Proof

Step	Hyp	Ref	Expression
1		nfnae	|- F/ z -. A. x x = y
2	1	sbf	|- ( [ w / z ] -. A. x x = y <-> -. A. x x = y )