Metamath Proof Explorer

Theorem pm2.42

Description: Theorem *2.42 of WhiteheadRussell p. 106. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm2.42 
|- ( ( -. ph \/ ( ph -> ps ) ) -> ( ph -> ps ) )

Proof

Step Hyp Ref Expression
1 pm2.21 
 |-  ( -. ph -> ( ph -> ps ) )
2 id 
 |-  ( ( ph -> ps ) -> ( ph -> ps ) )
3 1 2 jaoi 
 |-  ( ( -. ph \/ ( ph -> ps ) ) -> ( ph -> ps ) )