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Theorem 19.37 2255
Description: Theorem 19.37 of [Margaris] p. 90. See 19.37v 2077 for a version requiring fewer axioms. (Contributed by NM, 21-Jun-1993.)
Hypothesis
Ref Expression
19.37.1 𝑥𝜑
Assertion
Ref Expression
19.37 (∃𝑥(𝜑𝜓) ↔ (𝜑 → ∃𝑥𝜓))

Proof of Theorem 19.37
StepHypRef Expression
1 19.35 1956 . 2 (∃𝑥(𝜑𝜓) ↔ (∀𝑥𝜑 → ∃𝑥𝜓))
2 19.37.1 . . . 4 𝑥𝜑
3219.3 2223 . . 3 (∀𝑥𝜑𝜑)
43imbi1i 338 . 2 ((∀𝑥𝜑 → ∃𝑥𝜓) ↔ (𝜑 → ∃𝑥𝜓))
51, 4bitri 264 1 (∃𝑥(𝜑𝜓) ↔ (𝜑 → ∃𝑥𝜓))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 196  wal 1628  wex 1851  wnf 1855
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1869  ax-4 1884  ax-5 1990  ax-6 2056  ax-7 2092  ax-12 2202
This theorem depends on definitions:  df-bi 197  df-ex 1852  df-nf 1857
This theorem is referenced by:  bnj900  31331
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