Metamath Proof Explorer

Theorem olc

Description: Introduction of a disjunct. Axiom *1.3 of WhiteheadRussell p. 96. (Contributed by NM, 30-Aug-1993)

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

Proof

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