Theorem pm2.68 250

Description: Theorem *2.68 of [WhiteheadRussell] p. 108.

Assertion

Ref	Expression
pm2.68	|- (((ph -> ps) -> ps) -> (ph \/ ps))

Proof of Theorem pm2.68

Step	Hyp	Ref	Expression
1		dfor2 229	. 2 |- ((ph \/ ps) <-> ((ph -> ps) -> ps))
2	1	biimpr 152	1 |- (((ph -> ps) -> ps) -> (ph \/ ps))

Syntax hints:   -> wi 3   \/ wo 222

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-or 224

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