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Theorem pm11.7 38113
Description: Theorem *11.7 in [WhiteheadRussell] p. 166. (Contributed by Andrew Salmon, 24-May-2011.)
Assertion
Ref Expression
pm11.7 (∃𝑥𝑦(𝜑𝜑) ↔ ∃𝑥𝑦𝜑)

Proof of Theorem pm11.7
StepHypRef Expression
1 oridm 536 . 2 ((𝜑𝜑) ↔ 𝜑)
212exbii 1772 1 (∃𝑥𝑦(𝜑𝜑) ↔ ∃𝑥𝑦𝜑)
Colors of variables: wff setvar class
Syntax hints:  wb 196  wo 383  wex 1701
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734
This theorem depends on definitions:  df-bi 197  df-or 385  df-ex 1702
This theorem is referenced by: (None)
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