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Theorem undifabs 3878
 Description: Absorption of difference by union. (Contributed by NM, 18-Aug-2013.)
Assertion
Ref Expression
undifabs

Proof of Theorem undifabs
StepHypRef Expression
1 undif3 3740 . 2
2 unidm 3615 . . 3
32difeq1i 3585 . 2
4 difdif 3597 . 2
51, 3, 43eqtri 2462 1
 Colors of variables: wff setvar class Syntax hints:   wceq 1437   cdif 3439   cun 3440 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1665  ax-4 1678  ax-5 1751  ax-6 1797  ax-7 1841  ax-10 1889  ax-11 1894  ax-12 1907  ax-13 2055  ax-ext 2407 This theorem depends on definitions:  df-bi 188  df-or 371  df-an 372  df-tru 1440  df-ex 1660  df-nf 1664  df-sb 1790  df-clab 2415  df-cleq 2421  df-clel 2424  df-nfc 2579  df-rab 2791  df-v 3089  df-dif 3445  df-un 3447 This theorem is referenced by:  dfif5  3931  indifundif  27988
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