Theorem undm 3465

Description: De Morgan's law for union. Theorem 5.2(13) of [Stoll] p. 19. (Contributed by NM, 18-Aug-2004.)

Assertion

Ref	Expression
undm	|- ( _V \ ( A u. B ) ) = ( ( _V \ A ) i^i ( _V \ B ) )

Proof of Theorem undm

Step	Hyp	Ref	Expression
1		difundi 3459	1 |- ( _V \ ( A u. B ) ) = ( ( _V \ A ) i^i ( _V \ B ) )

Syntax hints:   = wceq 1397   _Vcvv 2802   \ cdif 3197   u. cun 3198   i^i cin 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-in1 619  ax-in2 620  ax-io 716  ax-5 1495  ax-7 1496  ax-gen 1497  ax-ie1 1541  ax-ie2 1542  ax-8 1552  ax-10 1553  ax-11 1554  ax-i12 1555  ax-bndl 1557  ax-4 1558  ax-17 1574  ax-i9 1578  ax-ial 1582  ax-i5r 1583  ax-ext 2213

This theorem depends on definitions:  df-bi 117  df-tru 1400  df-nf 1509  df-sb 1811  df-clab 2218  df-cleq 2224  df-clel 2227  df-nfc 2363  df-v 2804  df-dif 3202  df-un 3204  df-in 3206

This theorem is referenced by:  difun1  3467