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Theorem exanOLDOLD 2155
Description: Obsolete proof of exan 1775 as of 7-Jul-2021. (Contributed by NM, 18-Aug-1993.) (Proof shortened by Andrew Salmon, 25-May-2011.) (Proof shortened by Wolf Lammen, 13-Jan-2018.) (Proof modification is discouraged.) (New usage is discouraged.)
Hypothesis
Ref Expression
exanOLDOLD.1 (∃𝑥𝜑𝜓)
Assertion
Ref Expression
exanOLDOLD 𝑥(𝜑𝜓)

Proof of Theorem exanOLDOLD
StepHypRef Expression
1 exanOLDOLD.1 . 2 (∃𝑥𝜑𝜓)
21simpri 477 . . . 4 𝜓
32nfth 1718 . . 3 𝑥𝜓
4319.41 2090 . 2 (∃𝑥(𝜑𝜓) ↔ (∃𝑥𝜑𝜓))
51, 4mpbir 220 1 𝑥(𝜑𝜓)
Colors of variables: wff setvar class
Syntax hints:  wa 383  wex 1695
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-an 385  df-ex 1696  df-nf 1701
This theorem is referenced by: (None)
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