Metamath Proof Explorer


Theorem wl-ax11-lem7

Description: Lemma. (Contributed by Wolf Lammen, 30-Jun-2019)

Ref Expression
Assertion wl-ax11-lem7 x¬xx=yφ¬xx=yxφ

Proof

Step Hyp Ref Expression
1 nfna1 x¬xx=y
2 1 19.28 x¬xx=yφ¬xx=yxφ