Metamath Proof Explorer

Theorem pm2.5

Description: Theorem *2.5 of WhiteheadRussell p. 107. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm2.5 
|- ( -. ( ph -> ps ) -> ( -. ph -> ps ) )

Proof

Step Hyp Ref Expression
1 pm2.5g 
 |-  ( -. ( ph -> ps ) -> ( -. ph -> ps ) )