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Theorem eqeqan12rd 2053
Description: A useful inference for substituting definitions into an equality. (Contributed by NM, 9-Aug-1994.)
Hypotheses
Ref Expression
eqeqan12rd.1
eqeqan12rd.2  C  D
Assertion
Ref Expression
eqeqan12rd  C  D

Proof of Theorem eqeqan12rd
StepHypRef Expression
1 eqeqan12rd.1 . . 3
2 eqeqan12rd.2 . . 3  C  D
31, 2eqeqan12d 2052 . 2  C  D
43ancoms 255 1  C  D
Colors of variables: wff set class
Syntax hints:   wi 4   wa 97   wb 98   wceq 1242
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-5 1333  ax-gen 1335  ax-4 1397  ax-17 1416  ax-ext 2019
This theorem depends on definitions:  df-bi 110  df-cleq 2030
This theorem is referenced by: (None)
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