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Theorem ssint 3631
Description: Subclass of a class intersection. Theorem 5.11(viii) of [Monk1] p. 52 and its converse. (Contributed by NM, 14-Oct-1999.)
Assertion
Ref Expression
ssint  |-  ( A 
C_  |^| B  <->  A. x  e.  B  A  C_  x
)
Distinct variable groups:    x, A    x, B

Proof of Theorem ssint
Dummy variable  y is distinct from all other variables.
StepHypRef Expression
1 dfss3 2935 . 2  |-  ( A 
C_  |^| B  <->  A. y  e.  A  y  e.  |^| B )
2 vex 2560 . . . 4  |-  y  e. 
_V
32elint2 3622 . . 3  |-  ( y  e.  |^| B  <->  A. x  e.  B  y  e.  x )
43ralbii 2330 . 2  |-  ( A. y  e.  A  y  e.  |^| B  <->  A. y  e.  A  A. x  e.  B  y  e.  x )
5 ralcom 2473 . . 3  |-  ( A. y  e.  A  A. x  e.  B  y  e.  x  <->  A. x  e.  B  A. y  e.  A  y  e.  x )
6 dfss3 2935 . . . 4  |-  ( A 
C_  x  <->  A. y  e.  A  y  e.  x )
76ralbii 2330 . . 3  |-  ( A. x  e.  B  A  C_  x  <->  A. x  e.  B  A. y  e.  A  y  e.  x )
85, 7bitr4i 176 . 2  |-  ( A. y  e.  A  A. x  e.  B  y  e.  x  <->  A. x  e.  B  A  C_  x )
91, 4, 83bitri 195 1  |-  ( A 
C_  |^| B  <->  A. x  e.  B  A  C_  x
)
Colors of variables: wff set class
Syntax hints:    <-> wb 98    e. wcel 1393   A.wral 2306    C_ wss 2917   |^|cint 3615
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022
This theorem depends on definitions:  df-bi 110  df-tru 1246  df-nf 1350  df-sb 1646  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-ral 2311  df-v 2559  df-in 2924  df-ss 2931  df-int 3616
This theorem is referenced by:  ssintab  3632  ssintub  3633  iinpw  3742  trint  3869  fintm  5075  bj-ssom  10060
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