Theorem naev

Description: If some set variables can assume different values, then any two distinct set variables cannot always be the same. (Contributed by Wolf Lammen, 10-Aug-2019)

	Ref	Expression
Assertion	naev	$$⊢\neg \forall xx=y\to \neg \forall uu=v$$

Proof

Step	Hyp	Ref	Expression
1		aev	$$⊢\forall uu=v\to \forall xx=y$$
2	1	con3i	$$⊢\neg \forall xx=y\to \neg \forall uu=v$$