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Theorem 19.41vvvv 1893
Description: Theorem 19.41 of [Margaris] p. 90 with 4 quantifiers. (Contributed by FL, 14-Jul-2007.)
Assertion
Ref Expression
19.41vvvv (∃𝑤𝑥𝑦𝑧(𝜑𝜓) ↔ (∃𝑤𝑥𝑦𝑧𝜑𝜓))
Distinct variable groups:   𝜓,𝑤   𝜓,𝑥   𝜓,𝑦   𝜓,𝑧
Allowed substitution hints:   𝜑(𝑥,𝑦,𝑧,𝑤)

Proof of Theorem 19.41vvvv
StepHypRef Expression
1 19.41vvv 1892 . . 3 (∃𝑥𝑦𝑧(𝜑𝜓) ↔ (∃𝑥𝑦𝑧𝜑𝜓))
21exbii 1593 . 2 (∃𝑤𝑥𝑦𝑧(𝜑𝜓) ↔ ∃𝑤(∃𝑥𝑦𝑧𝜑𝜓))
3 19.41v 1890 . 2 (∃𝑤(∃𝑥𝑦𝑧𝜑𝜓) ↔ (∃𝑤𝑥𝑦𝑧𝜑𝜓))
42, 3bitri 183 1 (∃𝑤𝑥𝑦𝑧(𝜑𝜓) ↔ (∃𝑤𝑥𝑦𝑧𝜑𝜓))
Colors of variables: wff set class
Syntax hints:  wa 103  wb 104  wex 1480
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1435  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-4 1498  ax-17 1514  ax-ial 1522
This theorem depends on definitions:  df-bi 116
This theorem is referenced by: (None)
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