Theorem nfrmowOLD

Description: Obsolete version of nfrmow as of 21-Nov-2024. (Contributed by NM, 16-Jun-2017) (Revised by Gino Giotto, 10-Jan-2024) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypotheses	nfreuw.1	⊢ Ⅎ 𝑥 𝐴
	nfreuw.2	⊢ Ⅎ 𝑥 𝜑
Assertion	nfrmowOLD	⊢ Ⅎ 𝑥 ∃* 𝑦 ∈ 𝐴 𝜑

Proof

Step	Hyp	Ref	Expression
1		nfreuw.1	⊢ Ⅎ 𝑥 𝐴
2		nfreuw.2	⊢ Ⅎ 𝑥 𝜑
3		df-rmo	⊢ ( ∃* 𝑦 ∈ 𝐴 𝜑 ↔ ∃* 𝑦 ( 𝑦 ∈ 𝐴 ∧ 𝜑 ) )
4		nftru	⊢ Ⅎ 𝑦 ⊤
5		nfcvd	⊢ ( ⊤ → Ⅎ 𝑥 𝑦 )
6	1	a1i	⊢ ( ⊤ → Ⅎ 𝑥 𝐴 )
7	5 6	nfeld	⊢ ( ⊤ → Ⅎ 𝑥 𝑦 ∈ 𝐴 )
8	2	a1i	⊢ ( ⊤ → Ⅎ 𝑥 𝜑 )
9	7 8	nfand	⊢ ( ⊤ → Ⅎ 𝑥 ( 𝑦 ∈ 𝐴 ∧ 𝜑 ) )
10	4 9	nfmodv	⊢ ( ⊤ → Ⅎ 𝑥 ∃* 𝑦 ( 𝑦 ∈ 𝐴 ∧ 𝜑 ) )
11	10	mptru	⊢ Ⅎ 𝑥 ∃* 𝑦 ( 𝑦 ∈ 𝐴 ∧ 𝜑 )
12	3 11	nfxfr	⊢ Ⅎ 𝑥 ∃* 𝑦 ∈ 𝐴 𝜑