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Theorem pm4.81 357
Description: Theorem *4.81 of [WhiteheadRussell] p. 122.
Assertion
Ref Expression
pm4.81

Proof of Theorem pm4.81
StepHypRef Expression
1 pm2.18 100 . 2
2 pm2.24 99 . 2
31, 2impbii 178 1
Colors of variables: wff set class
Syntax hints:   wn 3   wi 4   wb 174
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 175
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