Theorem undm 3385

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 3379	1 |- ( _V \ ( A u. B ) ) = ( ( _V \ A ) i^i ( _V \ B ) )

Syntax hints:   = wceq 1348   _Vcvv 2730   \ cdif 3118   u. cun 3119   i^i cin 3120

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 609  ax-in2 610  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-tru 1351  df-nf 1454  df-sb 1756  df-clab 2157  df-cleq 2163  df-clel 2166  df-nfc 2301  df-v 2732  df-dif 3123  df-un 3125  df-in 3127

This theorem is referenced by:  difun1  3387