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Theorem iuniin 3931
Description: Law combining indexed union with indexed intersection. Eq. 14 in [KuratowskiMostowski] p. 109. This theorem also appears as the last example at http://en.wikipedia.org/wiki/Union%5F%28set%5Ftheory%29. (Contributed by NM, 17-Aug-2004.) (Proof shortened by Andrew Salmon, 25-Jul-2011.)
Assertion
Ref Expression
iuniin  |-  U_ x  e.  A  |^|_ y  e.  B  C  C_  |^|_ y  e.  B  U_ x  e.  A  C
Distinct variable groups:    x, y    y, A    x, B
Allowed substitution hints:    A( x)    B( y)    C( x, y)

Proof of Theorem iuniin
Dummy variable  z is distinct from all other variables.
StepHypRef Expression
1 r19.12 2669 . . . 4  |-  ( E. x  e.  A  A. y  e.  B  z  e.  C  ->  A. y  e.  B  E. x  e.  A  z  e.  C )
2 vex 2804 . . . . . 6  |-  z  e. 
_V
3 eliin 3926 . . . . . 6  |-  ( z  e.  _V  ->  (
z  e.  |^|_ y  e.  B  C  <->  A. y  e.  B  z  e.  C ) )
42, 3ax-mp 8 . . . . 5  |-  ( z  e.  |^|_ y  e.  B  C 
<-> 
A. y  e.  B  z  e.  C )
54rexbii 2581 . . . 4  |-  ( E. x  e.  A  z  e.  |^|_ y  e.  B  C 
<->  E. x  e.  A  A. y  e.  B  z  e.  C )
6 eliun 3925 . . . . 5  |-  ( z  e.  U_ x  e.  A  C  <->  E. x  e.  A  z  e.  C )
76ralbii 2580 . . . 4  |-  ( A. y  e.  B  z  e.  U_ x  e.  A  C 
<-> 
A. y  e.  B  E. x  e.  A  z  e.  C )
81, 5, 73imtr4i 257 . . 3  |-  ( E. x  e.  A  z  e.  |^|_ y  e.  B  C  ->  A. y  e.  B  z  e.  U_ x  e.  A  C )
9 eliun 3925 . . 3  |-  ( z  e.  U_ x  e.  A  |^|_ y  e.  B  C 
<->  E. x  e.  A  z  e.  |^|_ y  e.  B  C )
10 eliin 3926 . . . 4  |-  ( z  e.  _V  ->  (
z  e.  |^|_ y  e.  B  U_ x  e.  A  C  <->  A. y  e.  B  z  e.  U_ x  e.  A  C
) )
112, 10ax-mp 8 . . 3  |-  ( z  e.  |^|_ y  e.  B  U_ x  e.  A  C  <->  A. y  e.  B  z  e.  U_ x  e.  A  C )
128, 9, 113imtr4i 257 . 2  |-  ( z  e.  U_ x  e.  A  |^|_ y  e.  B  C  ->  z  e.  |^|_ y  e.  B  U_ x  e.  A  C )
1312ssriv 3197 1  |-  U_ x  e.  A  |^|_ y  e.  B  C  C_  |^|_ y  e.  B  U_ x  e.  A  C
Colors of variables: wff set class
Syntax hints:    <-> wb 176    e. wcel 1696   A.wral 2556   E.wrex 2557   _Vcvv 2801    C_ wss 3165   U_ciun 3921   |^|_ciin 3922
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-ral 2561  df-rex 2562  df-v 2803  df-in 3172  df-ss 3179  df-iun 3923  df-iin 3924
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