Metamath Proof Explorer

Theorem pm2.75

Description: Theorem *2.75 of WhiteheadRussell p. 108. (Contributed by NM, 3-Jan-2005) (Proof shortened by Wolf Lammen, 4-Jan-2013)

Ref Expression
Assertion pm2.75 
|- ( ( ph \/ ps ) -> ( ( ph \/ ( ps -> ch ) ) -> ( ph \/ ch ) ) )

Proof

Step Hyp Ref Expression
1 pm2.76 
 |-  ( ( ph \/ ( ps -> ch ) ) -> ( ( ph \/ ps ) -> ( ph \/ ch ) ) )
2 1 com12 
 |-  ( ( ph \/ ps ) -> ( ( ph \/ ( ps -> ch ) ) -> ( ph \/ ch ) ) )