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Theorem euor 1942
 Description: Introduce a disjunct into a uniqueness quantifier. (Contributed by NM, 21-Oct-2005.)
Hypothesis
Ref Expression
euor.1 (𝜑 → ∀𝑥𝜑)
Assertion
Ref Expression
euor ((¬ 𝜑 ∧ ∃!𝑥𝜓) → ∃!𝑥(𝜑𝜓))

Proof of Theorem euor
StepHypRef Expression
1 euor.1 . . . 4 (𝜑 → ∀𝑥𝜑)
21hbn 1560 . . 3 𝜑 → ∀𝑥 ¬ 𝜑)
3 biorf 673 . . 3 𝜑 → (𝜓 ↔ (𝜑𝜓)))
42, 3eubidh 1922 . 2 𝜑 → (∃!𝑥𝜓 ↔ ∃!𝑥(𝜑𝜓)))
54biimpa 284 1 ((¬ 𝜑 ∧ ∃!𝑥𝜓) → ∃!𝑥(𝜑𝜓))
 Colors of variables: wff set class Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 101   ∨ wo 639  ∀wal 1257  ∃!weu 1916 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-in1 554  ax-in2 555  ax-io 640  ax-5 1352  ax-gen 1354  ax-ie1 1398  ax-ie2 1399  ax-4 1416  ax-17 1435  ax-ial 1443 This theorem depends on definitions:  df-bi 114  df-tru 1262  df-fal 1265  df-eu 1919 This theorem is referenced by:  euorv  1943
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