Theorem pm5.41 176

Description: Theorem *5.41 of [WhiteheadRussell] p. 125.

Assertion

Ref	Expression
pm5.41	|- (((ph -> ps) -> (ph -> ch)) <-> (ph -> (ps -> ch)))

Proof of Theorem pm5.41

Step	Hyp	Ref	Expression
1		pm2.86 72	. 2 |- (((ph -> ps) -> (ph -> ch)) -> (ph -> (ps -> ch)))
2		ax-2 5	. 2 |- ((ph -> (ps -> ch)) -> ((ph -> ps) -> (ph -> ch)))
3	1, 2	impbii 164	1 |- (((ph -> ps) -> (ph -> ch)) <-> (ph -> (ps -> ch)))

Syntax hints:   -> wi 3   <-> wb 153

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 154

Copyright terms: Public domain