Metamath Proof Explorer

Theorem 3mix1

Description: Introduction in triple disjunction. (Contributed by NM, 4-Apr-1995)

Ref Expression
Assertion 3mix1 
|- ( ph -> ( ph \/ ps \/ ch ) )

Proof

Step Hyp Ref Expression
1 orc 
 |-  ( ph -> ( ph \/ ( ps \/ ch ) ) )
2 3orass 
 |-  ( ( ph \/ ps \/ ch ) <-> ( ph \/ ( ps \/ ch ) ) )
3 1 2 sylibr 
 |-  ( ph -> ( ph \/ ps \/ ch ) )