Metamath Proof Explorer


Theorem eqabrd

Description: Equality of a class variable and a class abstraction (deduction form of eqabb ). (Contributed by NM, 16-Nov-1995)

Ref Expression
Hypothesis eqabrd.1
|- ( ph -> A = { x | ps } )
Assertion eqabrd
|- ( ph -> ( x e. A <-> ps ) )

Proof

Step Hyp Ref Expression
1 eqabrd.1
 |-  ( ph -> A = { x | ps } )
2 1 eleq2d
 |-  ( ph -> ( x e. A <-> x e. { x | ps } ) )
3 abid
 |-  ( x e. { x | ps } <-> ps )
4 2 3 bitrdi
 |-  ( ph -> ( x e. A <-> ps ) )