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Theorem orduniorsuc 6550
Description: An ordinal class is either its union or the successor of its union. If we adopt the view that zero is a limit ordinal, this means every ordinal class is either a limit or a successor. (Contributed by NM, 13-Sep-2003.)
Assertion
Ref Expression
orduniorsuc  |-  ( Ord 
A  ->  ( A  =  U. A  \/  A  =  suc  U. A ) )

Proof of Theorem orduniorsuc
StepHypRef Expression
1 orduniss 4920 . . . . . 6  |-  ( Ord 
A  ->  U. A  C_  A )
2 orduni 6514 . . . . . . . 8  |-  ( Ord 
A  ->  Ord  U. A
)
3 ordelssne 4853 . . . . . . . 8  |-  ( ( Ord  U. A  /\  Ord  A )  ->  ( U. A  e.  A  <->  ( U. A  C_  A  /\  U. A  =/=  A
) ) )
42, 3mpancom 669 . . . . . . 7  |-  ( Ord 
A  ->  ( U. A  e.  A  <->  ( U. A  C_  A  /\  U. A  =/=  A ) ) )
54biimprd 223 . . . . . 6  |-  ( Ord 
A  ->  ( ( U. A  C_  A  /\  U. A  =/=  A )  ->  U. A  e.  A
) )
61, 5mpand 675 . . . . 5  |-  ( Ord 
A  ->  ( U. A  =/=  A  ->  U. A  e.  A ) )
7 ordsucss 6538 . . . . 5  |-  ( Ord 
A  ->  ( U. A  e.  A  ->  suc  U. A  C_  A ) )
86, 7syld 44 . . . 4  |-  ( Ord 
A  ->  ( U. A  =/=  A  ->  suc  U. A  C_  A )
)
9 ordsucuni 6549 . . . 4  |-  ( Ord 
A  ->  A  C_  suc  U. A )
108, 9jctild 543 . . 3  |-  ( Ord 
A  ->  ( U. A  =/=  A  ->  ( A  C_  suc  U. A  /\  suc  U. A  C_  A ) ) )
11 df-ne 2649 . . . 4  |-  ( A  =/=  U. A  <->  -.  A  =  U. A )
12 necom 2720 . . . 4  |-  ( A  =/=  U. A  <->  U. A  =/= 
A )
1311, 12bitr3i 251 . . 3  |-  ( -.  A  =  U. A  <->  U. A  =/=  A )
14 eqss 3478 . . 3  |-  ( A  =  suc  U. A  <->  ( A  C_  suc  U. A  /\  suc  U. A  C_  A ) )
1510, 13, 143imtr4g 270 . 2  |-  ( Ord 
A  ->  ( -.  A  =  U. A  ->  A  =  suc  U. A
) )
1615orrd 378 1  |-  ( Ord 
A  ->  ( A  =  U. A  \/  A  =  suc  U. A ) )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 184    \/ wo 368    /\ wa 369    = wceq 1370    e. wcel 1758    =/= wne 2647    C_ wss 3435   U.cuni 4198   Ord word 4825   suc csuc 4828
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1592  ax-4 1603  ax-5 1671  ax-6 1710  ax-7 1730  ax-8 1760  ax-9 1762  ax-10 1777  ax-11 1782  ax-12 1794  ax-13 1955  ax-ext 2432  ax-sep 4520  ax-nul 4528  ax-pr 4638  ax-un 6481
This theorem depends on definitions:  df-bi 185  df-or 370  df-an 371  df-3or 966  df-3an 967  df-tru 1373  df-ex 1588  df-nf 1591  df-sb 1703  df-eu 2266  df-mo 2267  df-clab 2440  df-cleq 2446  df-clel 2449  df-nfc 2604  df-ne 2649  df-ral 2803  df-rex 2804  df-rab 2807  df-v 3078  df-sbc 3293  df-dif 3438  df-un 3440  df-in 3442  df-ss 3449  df-pss 3451  df-nul 3745  df-if 3899  df-sn 3985  df-pr 3987  df-tp 3989  df-op 3991  df-uni 4199  df-br 4400  df-opab 4458  df-tr 4493  df-eprel 4739  df-po 4748  df-so 4749  df-fr 4786  df-we 4788  df-ord 4829  df-on 4830  df-suc 4832
This theorem is referenced by:  onuniorsuci  6559  oeeulem  7149  cantnfp1lem2  7997  cantnflem1  8007  cantnfp1lem2OLD  8023  cantnflem1OLD  8030  cnfcom2lem  8044  cnfcom2lemOLD  8052  dfac12lem1  8422  dfac12lem2  8423  ttukeylem3  8790  ttukeylem5  8792  ttukeylem6  8793  ordtoplem  28424  ordcmp  28436  aomclem5  29558
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