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Theorem pm4.43 967
Description: Theorem *4.43 of [WhiteheadRussell] p. 119. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 26-Nov-2012.)
Assertion
Ref Expression
pm4.43 (𝜑 ↔ ((𝜑𝜓) ∧ (𝜑 ∨ ¬ 𝜓)))

Proof of Theorem pm4.43
StepHypRef Expression
1 pm3.24 925 . . 3 ¬ (𝜓 ∧ ¬ 𝜓)
21biorfi 422 . 2 (𝜑 ↔ (𝜑 ∨ (𝜓 ∧ ¬ 𝜓)))
3 ordi 907 . 2 ((𝜑 ∨ (𝜓 ∧ ¬ 𝜓)) ↔ ((𝜑𝜓) ∧ (𝜑 ∨ ¬ 𝜓)))
42, 3bitri 264 1 (𝜑 ↔ ((𝜑𝜓) ∧ (𝜑 ∨ ¬ 𝜓)))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wb 196  wo 383  wa 384
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 197  df-or 385  df-an 386
This theorem is referenced by:  stoweidlem26  39571
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