Metamath Proof Explorer


Theorem rankdmr1

Description: A rank is a member of the cumulative hierarchy. (Contributed by Mario Carneiro, 17-Nov-2014)

Ref Expression
Assertion rankdmr1
|- ( rank ` A ) e. dom R1

Proof

Step Hyp Ref Expression
1 rankidb
 |-  ( A e. U. ( R1 " On ) -> A e. ( R1 ` suc ( rank ` A ) ) )
2 elfvdm
 |-  ( A e. ( R1 ` suc ( rank ` A ) ) -> suc ( rank ` A ) e. dom R1 )
3 1 2 syl
 |-  ( A e. U. ( R1 " On ) -> suc ( rank ` A ) e. dom R1 )
4 r1funlim
 |-  ( Fun R1 /\ Lim dom R1 )
5 4 simpri
 |-  Lim dom R1
6 limsuc
 |-  ( Lim dom R1 -> ( ( rank ` A ) e. dom R1 <-> suc ( rank ` A ) e. dom R1 ) )
7 5 6 ax-mp
 |-  ( ( rank ` A ) e. dom R1 <-> suc ( rank ` A ) e. dom R1 )
8 3 7 sylibr
 |-  ( A e. U. ( R1 " On ) -> ( rank ` A ) e. dom R1 )
9 rankvaln
 |-  ( -. A e. U. ( R1 " On ) -> ( rank ` A ) = (/) )
10 limomss
 |-  ( Lim dom R1 -> _om C_ dom R1 )
11 5 10 ax-mp
 |-  _om C_ dom R1
12 peano1
 |-  (/) e. _om
13 11 12 sselii
 |-  (/) e. dom R1
14 9 13 eqeltrdi
 |-  ( -. A e. U. ( R1 " On ) -> ( rank ` A ) e. dom R1 )
15 8 14 pm2.61i
 |-  ( rank ` A ) e. dom R1