Metamath Proof Explorer


Theorem nfrexw

Description: Bound-variable hypothesis builder for restricted quantification. (Contributed by NM, 1-Sep-1999) (Revised by Mario Carneiro, 7-Oct-2016) (Proof shortened by Wolf Lammen, 30-Dec-2019) Add disjoint variable condition to avoid ax-13 . See nfrex for a less restrictive version requiring more axioms. (Revised by Gino Giotto, 20-Jan-2024)

Ref Expression
Hypotheses nfralw.1 𝑥 𝐴
nfralw.2 𝑥 𝜑
Assertion nfrexw 𝑥𝑦𝐴 𝜑

Proof

Step Hyp Ref Expression
1 nfralw.1 𝑥 𝐴
2 nfralw.2 𝑥 𝜑
3 nftru 𝑦
4 1 a1i ( ⊤ → 𝑥 𝐴 )
5 2 a1i ( ⊤ → Ⅎ 𝑥 𝜑 )
6 3 4 5 nfrexdw ( ⊤ → Ⅎ 𝑥𝑦𝐴 𝜑 )
7 6 mptru 𝑥𝑦𝐴 𝜑