Theorem rmoeq1f

Description: Equality theorem for restricted at-most-one quantifier, with bound-variable hypotheses instead of distinct variable restrictions. (Contributed by Alexander van der Vekens, 17-Jun-2017)

	Ref	Expression
Hypotheses	rmoeq1f.1	$$⊢\underset{\_}{Ⅎ}xA$$
	rmoeq1f.2	$$⊢\underset{\_}{Ⅎ}xB$$
Assertion	rmoeq1f	$$⊢A=B\to \left({\exists }^{*}x\in A\phi \leftrightarrow {\exists }^{*}x\in B\phi \right)$$

Proof

Step	Hyp	Ref	Expression
1		rmoeq1f.1	$$⊢\underset{\_}{Ⅎ}xA$$
2		rmoeq1f.2	$$⊢\underset{\_}{Ⅎ}xB$$
3	1 2	nfeq	$$⊢ℲxA=B$$
4		eleq2	$$⊢A=B\to \left(x\in A\leftrightarrow x\in B\right)$$
5	4	anbi1d	$$⊢A=B\to \left(\left(x\in A\wedge \phi \right)\leftrightarrow \left(x\in B\wedge \phi \right)\right)$$
6	3 5	mobid	$$⊢A=B\to \left({\exists }^{*}x\left(x\in A\wedge \phi \right)\leftrightarrow {\exists }^{*}x\left(x\in B\wedge \phi \right)\right)$$
7		df-rmo	$$⊢{\exists }^{*}x\in A\phi \leftrightarrow {\exists }^{*}x\left(x\in A\wedge \phi \right)$$
8		df-rmo	$$⊢{\exists }^{*}x\in B\phi \leftrightarrow {\exists }^{*}x\left(x\in B\wedge \phi \right)$$
9	6 7 8	3bitr4g	$$⊢A=B\to \left({\exists }^{*}x\in A\phi \leftrightarrow {\exists }^{*}x\in B\phi \right)$$