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Theorem onelon 4306
Description: An element of an ordinal number is an ordinal number. Theorem 2.2(iii) of [BellMachover] p. 469. (Contributed by NM, 26-Oct-2003.)
Assertion
Ref Expression
onelon  |-  ( ( A  e.  On  /\  B  e.  A )  ->  B  e.  On )

Proof of Theorem onelon
StepHypRef Expression
1 eloni 4297 . 2  |-  ( A  e.  On  ->  Ord  A )
2 ordelon 4305 . 2  |-  ( ( Ord  A  /\  B  e.  A )  ->  B  e.  On )
31, 2sylan 281 1  |-  ( ( A  e.  On  /\  B  e.  A )  ->  B  e.  On )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 103    e. wcel 1480   Ord word 4284   Oncon0 4285
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 698  ax-5 1423  ax-7 1424  ax-gen 1425  ax-ie1 1469  ax-ie2 1470  ax-8 1482  ax-10 1483  ax-11 1484  ax-i12 1485  ax-bndl 1486  ax-4 1487  ax-17 1506  ax-i9 1510  ax-ial 1514  ax-i5r 1515  ax-ext 2121
This theorem depends on definitions:  df-bi 116  df-3an 964  df-tru 1334  df-nf 1437  df-sb 1736  df-clab 2126  df-cleq 2132  df-clel 2135  df-nfc 2270  df-ral 2421  df-rex 2422  df-v 2688  df-in 3077  df-ss 3084  df-uni 3737  df-tr 4027  df-iord 4288  df-on 4290
This theorem is referenced by:  oneli  4350  ssorduni  4403  unon  4427  tfrlemibacc  6223  tfrlemibxssdm  6224  tfrlemibfn  6225  tfrexlem  6231  tfr1onlemsucaccv  6238  tfrcllemsucaccv  6251  sucinc2  6342  oav2  6359  omv2  6361
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