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Theorem uniss 3669
Description: Subclass relationship for class union. Theorem 61 of [Suppes] p. 39. (Contributed by NM, 22-Mar-1998.) (Proof shortened by Andrew Salmon, 29-Jun-2011.)
Assertion
Ref Expression
uniss  |-  ( A 
C_  B  ->  U. A  C_ 
U. B )

Proof of Theorem uniss
Dummy variables  x  y are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 ssel 3017 . . . . 5  |-  ( A 
C_  B  ->  (
y  e.  A  -> 
y  e.  B ) )
21anim2d 330 . . . 4  |-  ( A 
C_  B  ->  (
( x  e.  y  /\  y  e.  A
)  ->  ( x  e.  y  /\  y  e.  B ) ) )
32eximdv 1808 . . 3  |-  ( A 
C_  B  ->  ( E. y ( x  e.  y  /\  y  e.  A )  ->  E. y
( x  e.  y  /\  y  e.  B
) ) )
4 eluni 3651 . . 3  |-  ( x  e.  U. A  <->  E. y
( x  e.  y  /\  y  e.  A
) )
5 eluni 3651 . . 3  |-  ( x  e.  U. B  <->  E. y
( x  e.  y  /\  y  e.  B
) )
63, 4, 53imtr4g 203 . 2  |-  ( A 
C_  B  ->  (
x  e.  U. A  ->  x  e.  U. B
) )
76ssrdv 3029 1  |-  ( A 
C_  B  ->  U. A  C_ 
U. B )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 102   E.wex 1426    e. wcel 1438    C_ wss 2997   U.cuni 3648
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070
This theorem depends on definitions:  df-bi 115  df-tru 1292  df-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-v 2621  df-in 3003  df-ss 3010  df-uni 3649
This theorem is referenced by:  unissi  3671  unissd  3672  intssuni2m  3707  relfld  4946
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