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Theorem pm5.5 326
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 325 . 2 (φ → (ψ ↔ (φψ)))
21bicomd 192 1 (φ → ((φψ) ↔ ψ))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 176
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
This theorem depends on definitions:  df-bi 177
This theorem is referenced by:  imim21b  356  elabgt  2982  sbceqal  3097
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