Metamath Proof Explorer

Theorem pm2.4

Description: Theorem *2.4 of WhiteheadRussell p. 106. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm2.4 
|- ( ( ph \/ ( ph \/ ps ) ) -> ( ph \/ ps ) )

Proof

Step Hyp Ref Expression
1 orc 
 |-  ( ph -> ( ph \/ ps ) )
2 id 
 |-  ( ( ph \/ ps ) -> ( ph \/ ps ) )
3 1 2 jaoi 
 |-  ( ( ph \/ ( ph \/ ps ) ) -> ( ph \/ ps ) )