Metamath Proof Explorer


Theorem pm2.43a

Description: Inference absorbing redundant antecedent. (Contributed by NM, 7-Nov-1995) (Proof shortened by Mel L. O'Cat, 28-Nov-2008)

Ref Expression
Hypothesis pm2.43a.1
|- ( ps -> ( ph -> ( ps -> ch ) ) )
Assertion pm2.43a
|- ( ps -> ( ph -> ch ) )

Proof

Step Hyp Ref Expression
1 pm2.43a.1
 |-  ( ps -> ( ph -> ( ps -> ch ) ) )
2 id
 |-  ( ps -> ps )
3 2 1 mpid
 |-  ( ps -> ( ph -> ch ) )