Metamath Proof Explorer

Theorem jarl

Description: Elimination of a nested antecedent. (Contributed by Wolf Lammen, 10-May-2013)

Ref Expression
Assertion jarl 
|- ( ( ( ph -> ps ) -> ch ) -> ( -. ph -> ch ) )

Proof

Step Hyp Ref Expression
1 pm2.21 
 |-  ( -. ph -> ( ph -> ps ) )
2 1 imim1i 
 |-  ( ( ( ph -> ps ) -> ch ) -> ( -. ph -> ch ) )