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Theorem elab3gf 3388
 Description: Membership in a class abstraction, with a weaker antecedent than elabgf 3380. (Contributed by NM, 6-Sep-2011.)
Hypotheses
Ref Expression
elab3gf.1 𝑥𝐴
elab3gf.2 𝑥𝜓
elab3gf.3 (𝑥 = 𝐴 → (𝜑𝜓))
Assertion
Ref Expression
elab3gf ((𝜓𝐴𝐵) → (𝐴 ∈ {𝑥𝜑} ↔ 𝜓))

Proof of Theorem elab3gf
StepHypRef Expression
1 elab3gf.1 . . . . 5 𝑥𝐴
2 elab3gf.2 . . . . 5 𝑥𝜓
3 elab3gf.3 . . . . 5 (𝑥 = 𝐴 → (𝜑𝜓))
41, 2, 3elabgf 3380 . . . 4 (𝐴 ∈ {𝑥𝜑} → (𝐴 ∈ {𝑥𝜑} ↔ 𝜓))
54ibi 256 . . 3 (𝐴 ∈ {𝑥𝜑} → 𝜓)
6 pm2.21 120 . . 3 𝜓 → (𝜓𝐴 ∈ {𝑥𝜑}))
75, 6impbid2 216 . 2 𝜓 → (𝐴 ∈ {𝑥𝜑} ↔ 𝜓))
81, 2, 3elabgf 3380 . 2 (𝐴𝐵 → (𝐴 ∈ {𝑥𝜑} ↔ 𝜓))
97, 8ja 173 1 ((𝜓𝐴𝐵) → (𝐴 ∈ {𝑥𝜑} ↔ 𝜓))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 196   = wceq 1523  Ⅎwnf 1748   ∈ wcel 2030  {cab 2637  Ⅎwnfc 2780 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-9 2039  ax-10 2059  ax-11 2074  ax-12 2087  ax-13 2282  ax-ext 2631 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-tru 1526  df-ex 1745  df-nf 1750  df-sb 1938  df-clab 2638  df-cleq 2644  df-clel 2647  df-nfc 2782  df-v 3233 This theorem is referenced by:  elab3g  3389
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