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 ) )