Theorem uneq12i 3381

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 ∪ 𝐶) = (𝐵 ∪ 𝐷)

Proof of Theorem uneq12i

Step	Hyp	Ref	Expression
1		uneq1i.1	. 2 ⊢ 𝐴 = 𝐵
2		uneq12i.2	. 2 ⊢ 𝐶 = 𝐷
3		uneq12 3378	. 2 ⊢ ((𝐴 = 𝐵 ∧ 𝐶 = 𝐷) → (𝐴 ∪ 𝐶) = (𝐵 ∪ 𝐷))
4	1, 2, 3	mp2an 430	1 ⊢ (𝐴 ∪ 𝐶) = (𝐵 ∪ 𝐷)

This proof depends on syntax axioms:   = wceq 1402   ∪ cun 3218

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 721  ax-5 1500  ax-7 1501  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-8 1557  ax-10 1558  ax-11 1559  ax-i12 1560  ax-bndl 1562  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587  ax-i5r 1588  ax-ext 2220

This proof depends on definitions:  df-bi 117  df-tru 1405  df-nf 1514  df-sb 1816  df-clab 2225  df-cleq 2231  df-clel 2234  df-nfc 2381  df-v 2823  df-un 3224

This theorem is used by:  indir  3480  difundir  3484  symdif1  3496  unrab  3504  rabun2  3512  dfif6  3640  dfif3  3654  unopab  4210  xpundi  4831  xpundir  4832  xpun  4836  dmun  4988  resundi  5076  resundir  5077  cnvun  5193  rnun  5196  imaundi  5200  imaundir  5201  dmtpop  5263  coundi  5289  coundir  5290  unidmrn  5320  dfdm2  5322  mptun  5515  fpr  5897  fvsnun2  5913  sbthlemi5  7278  djuunr  7406  djuun  7407  casedm  7426  djudm  7445  djuassen  7573  fz0to3un2pr  10530  fz0to4untppr  10531  fzo0to42pr  10638  xnn0nnen  10874