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Theorem hbab1 2749
Description: Bound-variable hypothesis builder for a class abstraction. (Contributed by NM, 26-May-1993.) (Proof shortened by Wolf Lammen, 25-Oct-2024.)
Assertion
Ref Expression
hbab1 (𝑦 ∈ {𝑥𝜑} → ∀𝑥 𝑦 ∈ {𝑥𝜑})
Distinct variable group:   𝑥,𝑦
Allowed substitution hints:   𝜑(𝑥, 𝑦)

Proof of Theorem hbab1
StepHypRef Expression
1 nfsab1 2748 . 2 𝑥 𝑦 ∈ {𝑥𝜑}
21nf5ri 2230 1 (𝑦 ∈ {𝑥𝜑} → ∀𝑥 𝑦 ∈ {𝑥𝜑})
Colors of variables:    wff setvar class
This proof depends on syntax axioms:  wi 4  wal 1567  wcel 2142  {cab 2740
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1824  ax-4 1838  ax-5 1939  ax-6 1996  ax-7 2037  ax-10 2175  ax-12 2212
This proof depends on definitions:  df-bi 210  df-an 401  df-or 861  df-ex 1809  df-nf 1813  df-sb 2096  df-clab 2741
This theorem is used by:  bnj1317  35218  bnj1318  35422  bj-nfsab1  37479
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