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Theorem pm4.25 753
Description: Theorem *4.25 of [WhiteheadRussell] p. 117. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm4.25 (𝜑 ↔ (𝜑𝜑))

Proof of Theorem pm4.25
StepHypRef Expression
1 oridm 752 . 2 ((𝜑𝜑) ↔ 𝜑)
21bicomi 131 1 (𝜑 ↔ (𝜑𝜑))
Colors of variables: wff set class
Syntax hints:  wb 104  wo 703
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-io 704
This theorem depends on definitions:  df-bi 116
This theorem is referenced by: (None)
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