Metamath Proof Explorer

Theorem biidd

Description: Principle of identity with antecedent. (Contributed by NM, 25-Nov-1995)

Ref Expression
Assertion biidd 
|- ( ph -> ( ps <-> ps ) )

Proof

Step Hyp Ref Expression
1 biid 
 |-  ( ps <-> ps )
2 1 a1i 
 |-  ( ph -> ( ps <-> ps ) )