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Metamath Proof Explorer

Theorem pm2.32

Description: Theorem *2.32 of WhiteheadRussell p. 105. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm2.32 
|- ( ( ( ph \/ ps ) \/ ch ) -> ( ph \/ ( ps \/ ch ) ) )

Proof

Step Hyp Ref Expression
1 orass 
 |-  ( ( ( ph \/ ps ) \/ ch ) <-> ( ph \/ ( ps \/ ch ) ) )
2 1 biimpi 
 |-  ( ( ( ph \/ ps ) \/ ch ) -> ( ph \/ ( ps \/ ch ) ) )