Metamath Proof Explorer

Theorem orc

Description: Introduction of a disjunct. Theorem *2.2 of WhiteheadRussell p. 104. (Contributed by NM, 30-Aug-1993)

Ref Expression
Assertion orc 
|- ( ph -> ( ph \/ ps ) )

Proof

Step Hyp Ref Expression
1 pm2.24 
 |-  ( ph -> ( -. ph -> ps ) )
2 1 orrd 
 |-  ( ph -> ( ph \/ ps ) )