Theorem exanali 1865

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(𝜑 → 𝜓))

Proof of Theorem exanali

Step	Hyp	Ref	Expression
1		annim 403	. . 3 ⊢ ((𝜑 ∧ ¬ 𝜓) ↔ ¬ (𝜑 → 𝜓))
2	1	exbii 1853	. 2 ⊢ (∃𝑥(𝜑 ∧ ¬ 𝜓) ↔ ∃𝑥 ¬ (𝜑 → 𝜓))
3		exnal 1832	. 2 ⊢ (∃𝑥 ¬ (𝜑 → 𝜓) ↔ ¬ ∀𝑥(𝜑 → 𝜓))
4	2, 3	bitri 274	1 ⊢ (∃𝑥(𝜑 ∧ ¬ 𝜓) ↔ ¬ ∀𝑥(𝜑 → 𝜓))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 205   ∧ wa 395  ∀wal 1539  ∃wex 1785

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1801  ax-4 1815

This theorem depends on definitions:  df-bi 206  df-an 396  df-ex 1786

This theorem is referenced by:  gencbval  3488  dfss6  3914  nss  3987  nssss  5373  brprcneu  6759  fvprc  6760  marypha1lem  9153  reclem2pr  10788  dftr6  33697  brsset  34170  dfon3  34173  dffun10  34195  elfuns  34196  ecinn0  36464  ax12indn  36936  expandrexn  41862  vk15.4j  42101  vk15.4jVD  42487