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Theorem intss 3830
Description: Intersection of subclasses. (Contributed by NM, 14-Oct-1999.)
Assertion
Ref Expression
intss  |-  ( A 
C_  B  ->  |^| B  C_ 
|^| A )

Proof of Theorem intss
Dummy variables  x  y are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 imim1 76 . . . . 5  |-  ( ( y  e.  A  -> 
y  e.  B )  ->  ( ( y  e.  B  ->  x  e.  y )  ->  (
y  e.  A  ->  x  e.  y )
) )
21al2imi 1438 . . . 4  |-  ( A. y ( y  e.  A  ->  y  e.  B )  ->  ( A. y ( y  e.  B  ->  x  e.  y )  ->  A. y
( y  e.  A  ->  x  e.  y ) ) )
3 vex 2715 . . . . 5  |-  x  e. 
_V
43elint 3815 . . . 4  |-  ( x  e.  |^| B  <->  A. y
( y  e.  B  ->  x  e.  y ) )
53elint 3815 . . . 4  |-  ( x  e.  |^| A  <->  A. y
( y  e.  A  ->  x  e.  y ) )
62, 4, 53imtr4g 204 . . 3  |-  ( A. y ( y  e.  A  ->  y  e.  B )  ->  (
x  e.  |^| B  ->  x  e.  |^| A
) )
76alrimiv 1854 . 2  |-  ( A. y ( y  e.  A  ->  y  e.  B )  ->  A. x
( x  e.  |^| B  ->  x  e.  |^| A ) )
8 dfss2 3117 . 2  |-  ( A 
C_  B  <->  A. y
( y  e.  A  ->  y  e.  B ) )
9 dfss2 3117 . 2  |-  ( |^| B  C_  |^| A  <->  A. x
( x  e.  |^| B  ->  x  e.  |^| A ) )
107, 8, 93imtr4i 200 1  |-  ( A 
C_  B  ->  |^| B  C_ 
|^| A )
Colors of variables: wff set class
Syntax hints:    -> wi 4   A.wal 1333    e. wcel 2128    C_ wss 3102   |^|cint 3809
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 1427  ax-7 1428  ax-gen 1429  ax-ie1 1473  ax-ie2 1474  ax-8 1484  ax-10 1485  ax-11 1486  ax-i12 1487  ax-bndl 1489  ax-4 1490  ax-17 1506  ax-i9 1510  ax-ial 1514  ax-i5r 1515  ax-ext 2139
This theorem depends on definitions:  df-bi 116  df-tru 1338  df-nf 1441  df-sb 1743  df-clab 2144  df-cleq 2150  df-clel 2153  df-nfc 2288  df-v 2714  df-in 3108  df-ss 3115  df-int 3810
This theorem is referenced by:  clsss  12588
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