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Theorem pm4.45 697
Description: Theorem *4.45 of [WhiteheadRussell] p. 119. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm4.45 (φ ↔ (φ (φ ψ)))

Proof of Theorem pm4.45
StepHypRef Expression
1 orc 632 . 2 (φ → (φ ψ))
21pm4.71i 371 1 (φ ↔ (φ (φ ψ)))
Colors of variables: wff set class
Syntax hints:   wa 97  wb 98   wo 628
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 629
This theorem depends on definitions:  df-bi 110
This theorem is referenced by:  dn1dc  866
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