Theorem eleq12d 2421

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

Hypotheses

Ref	Expression
eleq1d.1	|- (ph -> A = B)
eleq12d.2	|- (ph -> C = D)

Assertion

Ref	Expression
eleq12d	|- (ph -> (A e. C <-> B e. D))

Proof of Theorem eleq12d

Step	Hyp	Ref	Expression
1		eleq12d.2	. . 3 |- (ph -> C = D)
2	1	eleq2d 2420	. 2 |- (ph -> (A e. C <-> A e. D))
3		eleq1d.1	. . 3 |- (ph -> A = B)
4	3	eleq1d 2419	. 2 |- (ph -> (A e. D <-> B e. D))
5	2, 4	bitrd 244	1 |- (ph -> (A e. C <-> B e. D))

Syntax hints:   -> wi 4   <-> wb 176   = wceq 1642   e. wcel 1710

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-11 1746  ax-ext 2334

This theorem depends on definitions:  df-bi 177  df-an 360  df-ex 1542  df-cleq 2346  df-clel 2349

This theorem is referenced by:  cbvraldva2  2839  cbvrexdva2  2840  ru  3045  sbcel12g  3151  cbvralcsf  3198  cbvreucsf  3200  cbvrabcsf  3201  nenpw1pwlem2  6085  nmembers1  6270