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Theorem 19.43 1639
Description: Theorem 19.43 of [Margaris] p. 90. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Mario Carneiro, 2-Feb-2015.)
Assertion
Ref Expression
19.43 (∃𝑥(𝜑𝜓) ↔ (∃𝑥𝜑 ∨ ∃𝑥𝜓))

Proof of Theorem 19.43
StepHypRef Expression
1 hbe1 1506 . . . 4 (∃𝑥𝜑 → ∀𝑥𝑥𝜑)
2 hbe1 1506 . . . 4 (∃𝑥𝜓 → ∀𝑥𝑥𝜓)
31, 2hbor 1557 . . 3 ((∃𝑥𝜑 ∨ ∃𝑥𝜓) → ∀𝑥(∃𝑥𝜑 ∨ ∃𝑥𝜓))
4 19.8a 1601 . . . 4 (𝜑 → ∃𝑥𝜑)
5 19.8a 1601 . . . 4 (𝜓 → ∃𝑥𝜓)
64, 5orim12i 760 . . 3 ((𝜑𝜓) → (∃𝑥𝜑 ∨ ∃𝑥𝜓))
73, 6exlimih 1604 . 2 (∃𝑥(𝜑𝜓) → (∃𝑥𝜑 ∨ ∃𝑥𝜓))
8 orc 713 . . . 4 (𝜑 → (𝜑𝜓))
98eximi 1611 . . 3 (∃𝑥𝜑 → ∃𝑥(𝜑𝜓))
10 olc 712 . . . 4 (𝜓 → (𝜑𝜓))
1110eximi 1611 . . 3 (∃𝑥𝜓 → ∃𝑥(𝜑𝜓))
129, 11jaoi 717 . 2 ((∃𝑥𝜑 ∨ ∃𝑥𝜓) → ∃𝑥(𝜑𝜓))
137, 12impbii 126 1 (∃𝑥(𝜑𝜓) ↔ (∃𝑥𝜑 ∨ ∃𝑥𝜓))
Colors of variables: wff set class
Syntax hints:  wb 105  wo 709  wex 1503
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 710  ax-5 1458  ax-gen 1460  ax-ie1 1504  ax-ie2 1505  ax-4 1521  ax-ial 1545
This theorem depends on definitions:  df-bi 117
This theorem is referenced by:  19.44  1693  19.45  1694  19.34  1695  sborv  1902  r19.43  2648  rexun  3330  unipr  3838  uniun  3843  unopab  4097  dmun  4849  coundi  5145  coundir  5146
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