Theorem eleq12i 2275

Description: Inference from equality to equivalence of membership. (Contributed by NM, 31-May-1994.)

Hypotheses

Ref	Expression
eleq1i.1	|- A = B
eleq12i.2	|- C = D

Assertion

Ref	Expression
eleq12i	|- ( A e. C <-> B e. D )

Proof of Theorem eleq12i

Step	Hyp	Ref	Expression
1		eleq12i.2	. . 3 |- C = D
2	1	eleq2i 2274	. 2 |- ( A e. C <-> A e. D )
3		eleq1i.1	. . 3 |- A = B
4	3	eleq1i 2273	. 2 |- ( A e. D <-> B e. D )
5	2, 4	bitri 184	1 |- ( A e. C <-> B e. D )

Syntax hints:   <-> wb 105   = wceq 1373   e. wcel 2178

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1471  ax-gen 1473  ax-ie1 1517  ax-ie2 1518  ax-4 1534  ax-17 1550  ax-ial 1558  ax-ext 2189

This theorem depends on definitions:  df-bi 117  df-cleq 2200  df-clel 2203

This theorem is referenced by:  3eltr3g  2292  3eltr4g  2293  sbcel12g  3116  ennnfonelem1  12893  gausslemma2dlem4  15656