Metamath Proof Explorer

Theorem pm2.3

Description: Theorem *2.3 of WhiteheadRussell p. 104. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm2.3 
|- ( ( ph \/ ( ps \/ ch ) ) -> ( ph \/ ( ch \/ ps ) ) )

Proof

Step Hyp Ref Expression
1 pm1.4 
 |-  ( ( ps \/ ch ) -> ( ch \/ ps ) )
2 1 orim2i 
 |-  ( ( ph \/ ( ps \/ ch ) ) -> ( ph \/ ( ch \/ ps ) ) )