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Theorem dftr2 4238
Description: An alternate way of defining a transitive class. Exercise 7 of [TakeutiZaring] p. 40. (Contributed by NM, 24-Apr-1994.)
Assertion
Ref Expression
dftr2  |-  ( Tr  A  <->  A. x A. y
( ( x  e.  y  /\  y  e.  A )  ->  x  e.  A ) )
Distinct variable group:    x, y, A

Proof of Theorem dftr2
StepHypRef Expression
1 dfss2 3273 . 2  |-  ( U. A  C_  A  <->  A. x
( x  e.  U. A  ->  x  e.  A
) )
2 df-tr 4237 . 2  |-  ( Tr  A  <->  U. A  C_  A
)
3 19.23v 1903 . . . 4  |-  ( A. y ( ( x  e.  y  /\  y  e.  A )  ->  x  e.  A )  <->  ( E. y ( x  e.  y  /\  y  e.  A )  ->  x  e.  A ) )
4 eluni 3953 . . . . 5  |-  ( x  e.  U. A  <->  E. y
( x  e.  y  /\  y  e.  A
) )
54imbi1i 316 . . . 4  |-  ( ( x  e.  U. A  ->  x  e.  A )  <-> 
( E. y ( x  e.  y  /\  y  e.  A )  ->  x  e.  A ) )
63, 5bitr4i 244 . . 3  |-  ( A. y ( ( x  e.  y  /\  y  e.  A )  ->  x  e.  A )  <->  ( x  e.  U. A  ->  x  e.  A ) )
76albii 1572 . 2  |-  ( A. x A. y ( ( x  e.  y  /\  y  e.  A )  ->  x  e.  A )  <->  A. x ( x  e. 
U. A  ->  x  e.  A ) )
81, 2, 73bitr4i 269 1  |-  ( Tr  A  <->  A. x A. y
( ( x  e.  y  /\  y  e.  A )  ->  x  e.  A ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 177    /\ wa 359   A.wal 1546   E.wex 1547    e. wcel 1717    C_ wss 3256   U.cuni 3950   Tr wtr 4236
This theorem is referenced by:  dftr5  4239  trel  4243  ordelord  4537  suctr  4598  ordom  4787  hartogs  7439  card2on  7448  trcl  7590  tskwe  7763  ondomon  8364  dftr6  25124  elpotr  25154  hftr  25830  dford4  26784  tratrb  27956  trsbc  27961  truniALT  27962  sspwtr  28268  sspwtrALT  28269  sspwtrALT2  28270  pwtrVD  28271  pwtrrVD  28272  suctrALT2VD  28282  suctrALT2  28283  tratrbVD  28307  trsbcVD  28323  truniALTVD  28324  trintALTVD  28326  trintALT  28327  suctrALTcf  28368  suctrALTcfVD  28369  suctrALT3  28370
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1552  ax-5 1563  ax-17 1623  ax-9 1661  ax-8 1682  ax-6 1736  ax-7 1741  ax-11 1753  ax-12 1939  ax-ext 2361
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-tru 1325  df-ex 1548  df-nf 1551  df-sb 1656  df-clab 2367  df-cleq 2373  df-clel 2376  df-nfc 2505  df-v 2894  df-in 3263  df-ss 3270  df-uni 3951  df-tr 4237
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