Metamath Proof Explorer

Theorem pm2.621

Description: Theorem *2.621 of WhiteheadRussell p. 107. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm2.621 
|- ( ( ph -> ps ) -> ( ( ph \/ ps ) -> ps ) )

Proof

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