Theorem nfreu1

Description: The setvar x is not free in E! x e. A ph . (Contributed by NM, 19-Mar-1997)

	Ref	Expression
Assertion	nfreu1	$$⊢Ⅎx\exists !x\in A\phi$$

Proof

Step	Hyp	Ref	Expression
1		df-reu	$$⊢\exists !x\in A\phi \leftrightarrow \exists !x\left(x\in A\wedge \phi \right)$$
2		nfeu1	$$⊢Ⅎx\exists !x\left(x\in A\wedge \phi \right)$$
3	1 2	nfxfr	$$⊢Ⅎx\exists !x\in A\phi$$