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Theorem pm4.25 501
Description: Theorem *4.25 of [WhiteheadRussell] p. 117. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm4.25 (φ ↔ (φ φ))

Proof of Theorem pm4.25
StepHypRef Expression
1 oridm 500 . 2 ((φ φ) ↔ φ)
21bicomi 193 1 (φ ↔ (φ φ))
Colors of variables: wff setvar class
Syntax hints:  wb 176   wo 357
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 177  df-or 359
This theorem is referenced by: (None)
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