Metamath Proof Explorer

Theorem pm2.25

Description: Theorem *2.25 of WhiteheadRussell p. 104. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm2.25 
|- ( ph \/ ( ( ph \/ ps ) -> ps ) )

Proof

Step Hyp Ref Expression
1 orel1 
 |-  ( -. ph -> ( ( ph \/ ps ) -> ps ) )
2 1 orri 
 |-  ( ph \/ ( ( ph \/ ps ) -> ps ) )