Metamath Proof Explorer


Theorem csbieOLD

Description: Obsolete version of csbie as of 15-Oct-2024. (Contributed by AV, 2-Dec-2019) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Hypotheses csbieOLD.1
|- A e. _V
csbieOLD.2
|- ( x = A -> B = C )
Assertion csbieOLD
|- [_ A / x ]_ B = C

Proof

Step Hyp Ref Expression
1 csbieOLD.1
 |-  A e. _V
2 csbieOLD.2
 |-  ( x = A -> B = C )
3 nfcv
 |-  F/_ x C
4 1 3 2 csbief
 |-  [_ A / x ]_ B = C