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Theorem exbidOLD 2188
Description: Obsolete proof of exbid 2078 as of 6-Oct-2021. (Contributed by Mario Carneiro, 24-Sep-2016.) (Proof modification is discouraged.) (New usage is discouraged.)
Hypotheses
Ref Expression
exbidOLD.1 𝑥𝜑
exbidOLD.2 (𝜑 → (𝜓𝜒))
Assertion
Ref Expression
exbidOLD (𝜑 → (∃𝑥𝜓 ↔ ∃𝑥𝜒))

Proof of Theorem exbidOLD
StepHypRef Expression
1 exbidOLD.1 . . 3 𝑥𝜑
21nfriOLD 2177 . 2 (𝜑 → ∀𝑥𝜑)
3 exbidOLD.2 . 2 (𝜑 → (𝜓𝜒))
42, 3exbidh 1781 1 (𝜑 → (∃𝑥𝜓 ↔ ∃𝑥𝜒))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 195  wex 1695  wnfOLD 1700
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-12 2034
This theorem depends on definitions:  df-bi 196  df-ex 1696  df-nfOLD 1712
This theorem is referenced by: (None)
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