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Theorem opeq1OLD 4767
 Description: Obsolete version of opeq1 4766 as of 25-May-2024. (Contributed by NM, 25-Jun-1998.) (Revised by Mario Carneiro, 26-Apr-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
opeq1OLD (𝐴 = 𝐵 → ⟨𝐴, 𝐶⟩ = ⟨𝐵, 𝐶⟩)

Proof of Theorem opeq1OLD
StepHypRef Expression
1 eleq1 2880 . . . 4 (𝐴 = 𝐵 → (𝐴 ∈ V ↔ 𝐵 ∈ V))
21anbi1d 632 . . 3 (𝐴 = 𝐵 → ((𝐴 ∈ V ∧ 𝐶 ∈ V) ↔ (𝐵 ∈ V ∧ 𝐶 ∈ V)))
3 sneq 4538 . . . 4 (𝐴 = 𝐵 → {𝐴} = {𝐵})
4 preq1 4632 . . . 4 (𝐴 = 𝐵 → {𝐴, 𝐶} = {𝐵, 𝐶})
53, 4preq12d 4640 . . 3 (𝐴 = 𝐵 → {{𝐴}, {𝐴, 𝐶}} = {{𝐵}, {𝐵, 𝐶}})
62, 5ifbieq1d 4451 . 2 (𝐴 = 𝐵 → if((𝐴 ∈ V ∧ 𝐶 ∈ V), {{𝐴}, {𝐴, 𝐶}}, ∅) = if((𝐵 ∈ V ∧ 𝐶 ∈ V), {{𝐵}, {𝐵, 𝐶}}, ∅))
7 dfopif 4763 . 2 𝐴, 𝐶⟩ = if((𝐴 ∈ V ∧ 𝐶 ∈ V), {{𝐴}, {𝐴, 𝐶}}, ∅)
8 dfopif 4763 . 2 𝐵, 𝐶⟩ = if((𝐵 ∈ V ∧ 𝐶 ∈ V), {{𝐵}, {𝐵, 𝐶}}, ∅)
96, 7, 83eqtr4g 2861 1 (𝐴 = 𝐵 → ⟨𝐴, 𝐶⟩ = ⟨𝐵, 𝐶⟩)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 399   = wceq 1538   ∈ wcel 2112  Vcvv 3444  ∅c0 4246  ifcif 4428  {csn 4528  {cpr 4530  ⟨cop 4534 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2114  ax-9 2122  ax-10 2143  ax-11 2159  ax-12 2176  ax-ext 2773 This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-3an 1086  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2070  df-clab 2780  df-cleq 2794  df-clel 2873  df-nfc 2941  df-rab 3118  df-v 3446  df-dif 3887  df-un 3889  df-in 3891  df-ss 3901  df-nul 4247  df-if 4429  df-sn 4529  df-pr 4531  df-op 4535 This theorem is referenced by: (None)
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