Metamath Proof Explorer


Theorem cbvmptvOLD

Description: Obsolete version of cbvmptv as of 17-Nov-2024. (Contributed by Mario Carneiro, 19-Feb-2013) Add disjoint variable condition to avoid ax-13 . See cbvmptvg for a less restrictive version requiring more axioms. (Revised by Gino Giotto, 17-Jan-2024) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Hypothesis cbvmptvOLD.1
|- ( x = y -> B = C )
Assertion cbvmptvOLD
|- ( x e. A |-> B ) = ( y e. A |-> C )

Proof

Step Hyp Ref Expression
1 cbvmptvOLD.1
 |-  ( x = y -> B = C )
2 nfcv
 |-  F/_ y B
3 nfcv
 |-  F/_ x C
4 2 3 1 cbvmpt
 |-  ( x e. A |-> B ) = ( y e. A |-> C )