Theorem eleq12 2691

Description: Equality implies equivalence of membership. (Contributed by NM, 31-May-1999.)

Assertion

Ref	Expression
eleq12	|- ( ( A = B /\ C = D ) -> ( A e. C <-> B e. D ) )

Proof of Theorem eleq12

Step	Hyp	Ref	Expression
1		eleq1 2689	. 2 |- ( A = B -> ( A e. C <-> B e. C ) )
2		eleq2 2690	. 2 |- ( C = D -> ( B e. C <-> B e. D ) )
3	1, 2	sylan9bb 736	1 |- ( ( A = B /\ C = D ) -> ( A e. C <-> B e. D ) )

Syntax hints:   -> wi 4   <-> wb 196   /\ wa 384   = wceq 1483   e. wcel 1990

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-9 1999  ax-ext 2602

This theorem depends on definitions:  df-bi 197  df-an 386  df-ex 1705  df-cleq 2615  df-clel 2618

This theorem is referenced by:  trel  4759  pwnss  4830  epelg  5030  preleq  8514  oemapval  8580  cantnf  8590  wemapwe  8594  nnsdomel  8816  cldval  20827  isufil  21707  umgr2v2enb1  26422  issiga  30174  matunitlindf  33407  wepwsolem  37612  aomclem8  37631  nelbr  41291