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Theorem pm5.5 241
Description: Theorem *5.5 of [WhiteheadRussell] p. 125. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm5.5 (𝜑 → ((𝜑𝜓) ↔ 𝜓))

Proof of Theorem pm5.5
StepHypRef Expression
1 biimt 240 . 2 (𝜑 → (𝜓 ↔ (𝜑𝜓)))
21bicomd 140 1 (𝜑 → ((𝜑𝜓) ↔ 𝜓))
Colors of variables: wff set class
Syntax hints:  wi 4  wb 104
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107
This theorem depends on definitions:  df-bi 116
This theorem is referenced by:  imim21b  251  elabgt  2797  sbceqal  2934  dffun8  5119  ordiso2  6886  indstr2  9355  dfgcd2  11609
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