Theorem uneq12i 3316

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 3313	. 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 1364   u. cun 3155

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 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-v 2765  df-un 3161

This theorem is referenced by:  indir  3413  difundir  3417  symdif1  3429  unrab  3435  rabun2  3443  dfif6  3564  dfif3  3575  unopab  4113  xpundi  4720  xpundir  4721  xpun  4725  dmun  4874  resundi  4960  resundir  4961  cnvun  5076  rnun  5079  imaundi  5083  imaundir  5084  dmtpop  5146  coundi  5172  coundir  5173  unidmrn  5203  dfdm2  5205  mptun  5392  fpr  5747  fvsnun2  5763  sbthlemi5  7036  djuunr  7141  djuun  7142  casedm  7161  djudm  7180  djuassen  7300  fz0to3un2pr  10215  fz0to4untppr  10216  fzo0to42pr  10313  xnn0nnen  10546