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Theorem undifabs 3544
 Description: Absorption of difference by union. (Contributed by NM, 18-Aug-2013.)
Assertion
Ref Expression
undifabs

Proof of Theorem undifabs
StepHypRef Expression
1 undif3 3442 . 2
2 unidm 3331 . . 3
32difeq1i 3303 . 2
4 difdif 3315 . 2
51, 3, 43eqtri 2320 1
 Colors of variables: wff set class Syntax hints:   wceq 1632   cdif 3162   cun 3163 This theorem is referenced by:  dfif5  3590 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1536  ax-5 1547  ax-17 1606  ax-9 1644  ax-8 1661  ax-6 1715  ax-7 1720  ax-11 1727  ax-12 1878  ax-ext 2277 This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-tru 1310  df-ex 1532  df-nf 1535  df-sb 1639  df-clab 2283  df-cleq 2289  df-clel 2292  df-nfc 2421  df-rab 2565  df-v 2803  df-dif 3168  df-un 3170
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