Theorem uneq12i 3375

Description: Equality inference for union of two classes. (Contributed by NM, 12-Aug-2004.) (Proof shortened by Eric Schmidt, 26-Jan-2007.)

Hypotheses

Ref	Expression
uneq1i.1	|- A = B
uneq12i.2	|- C = D

Assertion

Ref	Expression
uneq12i	|- ( A u. C ) = ( B u. D )

Proof of Theorem uneq12i

Step	Hyp	Ref	Expression
1		uneq1i.1	. 2 |- A = B
2		uneq12i.2	. 2 |- C = D
3		uneq12 3372	. 2 |- ( ( A = B /\ C = D ) -> ( A u. C ) = ( B u. D ) )
4	1, 2, 3	mp2an 426	1 |- ( A u. C ) = ( B u. D )

Syntax hints:   = wceq 1398   u. cun 3212

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-io 717  ax-5 1496  ax-7 1497  ax-gen 1498  ax-ie1 1542  ax-ie2 1543  ax-8 1553  ax-10 1554  ax-11 1555  ax-i12 1556  ax-bndl 1558  ax-4 1559  ax-17 1575  ax-i9 1579  ax-ial 1583  ax-i5r 1584  ax-ext 2216

This theorem depends on definitions:  df-bi 117  df-tru 1401  df-nf 1510  df-sb 1812  df-clab 2221  df-cleq 2227  df-clel 2230  df-nfc 2375  df-v 2817  df-un 3218

This theorem is referenced by:  indir  3474  difundir  3478  symdif1  3490  unrab  3496  rabun2  3504  dfif6  3626  dfif3  3640  unopab  4194  xpundi  4811  xpundir  4812  xpun  4816  dmun  4968  resundi  5056  resundir  5057  cnvun  5173  rnun  5176  imaundi  5180  imaundir  5181  dmtpop  5243  coundi  5269  coundir  5270  unidmrn  5300  dfdm2  5302  mptun  5495  fpr  5871  fvsnun2  5887  sbthlemi5  7244  djuunr  7370  djuun  7371  casedm  7390  djudm  7409  djuassen  7537  fz0to3un2pr  10479  fz0to4untppr  10480  fzo0to42pr  10587  xnn0nnen  10823