Theorem hbnae

Description: All variables are effectively bound in a distinct variable specifier. Lemma L19 in Megill p. 446 (p. 14 of the preprint). Usage of this theorem is discouraged because it depends on ax-13 . Use the weaker hbnaev when possible. (Contributed by NM, 13-May-1993) (New usage is discouraged.)

	Ref	Expression
Assertion	hbnae	$$⊢\neg \forall xx=y\to \forall z\neg \forall xx=y$$

Proof

Step	Hyp	Ref	Expression
1		hbae	$$⊢\forall xx=y\to \forall z\forall xx=y$$
2	1	hbn	$$⊢\neg \forall xx=y\to \forall z\neg \forall xx=y$$