Theorem uneq12i 3361

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 3358	. 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 3199

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 2213

This theorem depends on definitions:  df-bi 117  df-tru 1401  df-nf 1510  df-sb 1811  df-clab 2218  df-cleq 2224  df-clel 2227  df-nfc 2364  df-v 2805  df-un 3205

This theorem is referenced by:  indir  3458  difundir  3462  symdif1  3474  unrab  3480  rabun2  3488  dfif6  3609  dfif3  3623  unopab  4173  xpundi  4788  xpundir  4789  xpun  4793  dmun  4944  resundi  5032  resundir  5033  cnvun  5149  rnun  5152  imaundi  5156  imaundir  5157  dmtpop  5219  coundi  5245  coundir  5246  unidmrn  5276  dfdm2  5278  mptun  5471  fpr  5844  fvsnun2  5860  sbthlemi5  7203  djuunr  7325  djuun  7326  casedm  7345  djudm  7364  djuassen  7492  fz0to3un2pr  10420  fz0to4untppr  10421  fzo0to42pr  10528  xnn0nnen  10762