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Theorem exanali 1863
Description: A transformation of quantifiers and logical connectives. (Contributed by NM, 25-Mar-1996.) (Proof shortened by Wolf Lammen, 4-Sep-2014.)
Assertion
Ref Expression
exanali (∃𝑥(𝜑 ∧ ¬ 𝜓) ↔ ¬ ∀𝑥(𝜑𝜓))

Proof of Theorem exanali
StepHypRef Expression
1 annim 405 . . 3 ((𝜑 ∧ ¬ 𝜓) ↔ ¬ (𝜑𝜓))
21exbii 1851 . 2 (∃𝑥(𝜑 ∧ ¬ 𝜓) ↔ ∃𝑥 ¬ (𝜑𝜓))
3 exnal 1830 . 2 (∃𝑥 ¬ (𝜑𝜓) ↔ ¬ ∀𝑥(𝜑𝜓))
42, 3bitri 275 1 (∃𝑥(𝜑 ∧ ¬ 𝜓) ↔ ¬ ∀𝑥(𝜑𝜓))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 205  wa 397  wal 1540  wex 1782
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812
This theorem depends on definitions:  df-bi 206  df-an 398  df-ex 1783
This theorem is referenced by:  gencbval  3538  dfss6  3972  nss  4047  nssss  5456  brprcneu  6882  brprcneuALT  6883  marypha1lem  9428  reclem2pr  11043  dftr6  34752  brsset  34892  dfon3  34895  dffun10  34917  elfuns  34918  ecinn0  37270  ax12indn  37861  expandrexn  43098  vk15.4j  43337  vk15.4jVD  43723
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