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Theorem moim 2530
Description: The at-most-one quantifier reverses implication. (Contributed by NM, 22-Apr-1995.)
Assertion
Ref Expression
moim (∀𝑥(𝜑𝜓) → (∃*𝑥𝜓 → ∃*𝑥𝜑))

Proof of Theorem moim
Dummy variable 𝑦 is distinct from all other variables.
StepHypRef Expression
1 imim1 83 . . . 4 ((𝜑𝜓) → ((𝜓𝑥 = 𝑦) → (𝜑𝑥 = 𝑦)))
21al2imi 1809 . . 3 (∀𝑥(𝜑𝜓) → (∀𝑥(𝜓𝑥 = 𝑦) → ∀𝑥(𝜑𝑥 = 𝑦)))
32eximdv 1912 . 2 (∀𝑥(𝜑𝜓) → (∃𝑦𝑥(𝜓𝑥 = 𝑦) → ∃𝑦𝑥(𝜑𝑥 = 𝑦)))
4 df-mo 2526 . 2 (∃*𝑥𝜓 ↔ ∃𝑦𝑥(𝜓𝑥 = 𝑦))
5 df-mo 2526 . 2 (∃*𝑥𝜑 ↔ ∃𝑦𝑥(𝜑𝑥 = 𝑦))
63, 4, 53imtr4g 296 1 (∀𝑥(𝜑𝜓) → (∃*𝑥𝜓 → ∃*𝑥𝜑))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wal 1531  wex 1773  ∃*wmo 2524
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905
This theorem depends on definitions:  df-bi 206  df-ex 1774  df-mo 2526
This theorem is referenced by:  moimdv  2532  mobi  2533  euimmo  2604  moexexlem  2614  rmoim  3729  rmoimi2  3732  ssrmof  4042  disjss3  5138  funmo  6554  funmoOLD  6555  uptx  23453  taylf  26216
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