Metamath Proof Explorer

Theorem ori

Description: Infer implication from disjunction. (Contributed by NM, 11-Jun-1994)

Ref Expression
Hypothesis ori.1 
|- ( ph \/ ps )
Assertion ori 
|- ( -. ph -> ps )

Proof

Step Hyp Ref Expression
1 ori.1 
 |-  ( ph \/ ps )
2 df-or 
 |-  ( ( ph \/ ps ) <-> ( -. ph -> ps ) )
3 1 2 mpbi 
 |-  ( -. ph -> ps )