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Theorem uniss 3807
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 3134 . . . . 5  |-  ( A 
C_  B  ->  (
y  e.  A  -> 
y  e.  B ) )
21anim2d 335 . . . 4  |-  ( A 
C_  B  ->  (
( x  e.  y  /\  y  e.  A
)  ->  ( x  e.  y  /\  y  e.  B ) ) )
32eximdv 1867 . . 3  |-  ( A 
C_  B  ->  ( E. y ( x  e.  y  /\  y  e.  A )  ->  E. y
( x  e.  y  /\  y  e.  B
) ) )
4 eluni 3789 . . 3  |-  ( x  e.  U. A  <->  E. y
( x  e.  y  /\  y  e.  A
) )
5 eluni 3789 . . 3  |-  ( x  e.  U. B  <->  E. y
( x  e.  y  /\  y  e.  B
) )
63, 4, 53imtr4g 204 . 2  |-  ( A 
C_  B  ->  (
x  e.  U. A  ->  x  e.  U. B
) )
76ssrdv 3146 1  |-  ( A 
C_  B  ->  U. A  C_ 
U. B )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 103   E.wex 1479    e. wcel 2135    C_ wss 3114   U.cuni 3786
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-io 699  ax-5 1434  ax-7 1435  ax-gen 1436  ax-ie1 1480  ax-ie2 1481  ax-8 1491  ax-10 1492  ax-11 1493  ax-i12 1494  ax-bndl 1496  ax-4 1497  ax-17 1513  ax-i9 1517  ax-ial 1521  ax-i5r 1522  ax-ext 2146
This theorem depends on definitions:  df-bi 116  df-tru 1345  df-nf 1448  df-sb 1750  df-clab 2151  df-cleq 2157  df-clel 2160  df-nfc 2295  df-v 2726  df-in 3120  df-ss 3127  df-uni 3787
This theorem is referenced by:  unissi  3809  unissd  3810  intssuni2m  3845  relfld  5129  tgcl  12662  distop  12683
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