Metamath Proof Explorer


Theorem elabOLD

Description: Obsolete version of elab as of 5-Oct-2024. (Contributed by NM, 1-Aug-1994) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Hypotheses elab.1
|- A e. _V
elab.2
|- ( x = A -> ( ph <-> ps ) )
Assertion elabOLD
|- ( A e. { x | ph } <-> ps )

Proof

Step Hyp Ref Expression
1 elab.1
 |-  A e. _V
2 elab.2
 |-  ( x = A -> ( ph <-> ps ) )
3 nfv
 |-  F/ x ps
4 3 1 2 elabf
 |-  ( A e. { x | ph } <-> ps )