Metamath Proof Explorer

Theorem pm5.35

Description: Theorem *5.35 of WhiteheadRussell p. 125. Closed form of 2thd . (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm5.35 
|- ( ( ( ph -> ps ) /\ ( ph -> ch ) ) -> ( ph -> ( ps <-> ch ) ) )

Proof

Step Hyp Ref Expression
1 pm5.1 
 |-  ( ( ( ph -> ps ) /\ ( ph -> ch ) ) -> ( ( ph -> ps ) <-> ( ph -> ch ) ) )
2 1 pm5.74rd 
 |-  ( ( ( ph -> ps ) /\ ( ph -> ch ) ) -> ( ph -> ( ps <-> ch ) ) )