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Theorem 19.37 2138
Description: Theorem 19.37 of [Margaris] p. 90. See 19.37v 1966 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 1845 . 2 (∃𝑥(𝜑𝜓) ↔ (∀𝑥𝜑 → ∃𝑥𝜓))
2 19.37.1 . . . 4 𝑥𝜑
3219.3 2107 . . 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 1521  wex 1744  wnf 1748
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-12 2087
This theorem depends on definitions:  df-bi 197  df-ex 1745  df-nf 1750
This theorem is referenced by:  bnj900  31125
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