Theorem uneq12i 3279

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 3276	. 2 |- ( ( A = B /\ C = D ) -> ( A u. C ) = ( B u. D ) )
4	1, 2, 3	mp2an 424	1 |- ( A u. C ) = ( B u. D )

Syntax hints:   = wceq 1348   u. cun 3119

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-tru 1351  df-nf 1454  df-sb 1756  df-clab 2157  df-cleq 2163  df-clel 2166  df-nfc 2301  df-v 2732  df-un 3125

This theorem is referenced by:  indir  3376  difundir  3380  symdif1  3392  unrab  3398  rabun2  3406  dfif6  3528  dfif3  3539  unopab  4068  xpundi  4667  xpundir  4668  xpun  4672  dmun  4818  resundi  4904  resundir  4905  cnvun  5016  rnun  5019  imaundi  5023  imaundir  5024  dmtpop  5086  coundi  5112  coundir  5113  unidmrn  5143  dfdm2  5145  mptun  5329  fpr  5678  fvsnun2  5694  sbthlemi5  6938  djuunr  7043  djuun  7044  casedm  7063  djudm  7082  djuassen  7194  fz0to3un2pr  10079  fz0to4untppr  10080  fzo0to42pr  10176