Theorem orbi1 686

Description: Theorem *4.37 of [WhiteheadRussell] p. 118. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
orbi1	|- ((ph <-> ps) -> ((ph \/ ch) <-> (ps \/ ch)))

Proof of Theorem orbi1

Step	Hyp	Ref	Expression
1		id 19	. 2 |- ((ph <-> ps) -> (ph <-> ps))
2	1	orbi1d 683	1 |- ((ph <-> ps) -> ((ph \/ ch) <-> (ps \/ ch)))

Syntax hints:   -> wi 4   <-> wb 176   \/ wo 357

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 177  df-or 359

This theorem is referenced by: (None)