Theorem pm5.5 732

Description: Theorem *5.5 of [WhiteheadRussell] p. 125.

Assertion

Ref	Expression
pm5.5	|- (ph -> ((ph -> ps) <-> ps))

Proof of Theorem pm5.5

Step	Hyp	Ref	Expression
1		biimt 731	. 2 |- (ph -> (ps <-> (ph -> ps)))
2	1	bicomd 521	1 |- (ph -> ((ph -> ps) <-> ps))

Syntax hints:   -> wi 3   <-> wb 146

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7

This theorem depends on definitions:  df-bi 147  df-an 225

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