Theorem ssorduni 6985

Description: The union of a class of ordinal numbers is ordinal. Proposition 7.19 of [TakeutiZaring] p. 40. (Contributed by NM, 30-May-1994.) (Proof shortened by Andrew Salmon, 12-Aug-2011.)

Assertion

Ref	Expression
ssorduni	|- ( A C_ On -> Ord U. A )

Proof of Theorem ssorduni

Dummy variables x y are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		eluni2 4440	. . . . 5 |- ( x e. U. A <-> E. y e. A x e. y )
2		ssel 3597	. . . . . . . . 9 |- ( A C_ On -> ( y e. A -> y e. On ) )
3		onelss 5766	. . . . . . . . 9 |- ( y e. On -> ( x e. y -> x C_ y ) )
4	2, 3	syl6 35	. . . . . . . 8 |- ( A C_ On -> ( y e. A -> ( x e. y -> x C_ y ) ) )
5		anc2r 579	. . . . . . . 8 |- ( ( y e. A -> ( x e. y -> x C_ y ) ) -> ( y e. A -> ( x e. y -> ( x C_ y /\ y e. A ) ) ) )
6	4, 5	syl 17	. . . . . . 7 |- ( A C_ On -> ( y e. A -> ( x e. y -> ( x C_ y /\ y e. A ) ) ) )
7		ssuni 4459	. . . . . . 7 |- ( ( x C_ y /\ y e. A ) -> x C_ U. A )
8	6, 7	syl8 76	. . . . . 6 |- ( A C_ On -> ( y e. A -> ( x e. y -> x C_ U. A ) ) )
9	8	rexlimdv 3030	. . . . 5 |- ( A C_ On -> ( E. y e. A x e. y -> x C_ U. A ) )
10	1, 9	syl5bi 232	. . . 4 |- ( A C_ On -> ( x e. U. A -> x C_ U. A ) )
11	10	ralrimiv 2965	. . 3 |- ( A C_ On -> A. x e. U. A x C_ U. A )
12		dftr3 4756	. . 3 |- ( Tr U. A <-> A. x e. U. A x C_ U. A )
13	11, 12	sylibr 224	. 2 |- ( A C_ On -> Tr U. A )
14		onelon 5748	. . . . . . 7 |- ( ( y e. On /\ x e. y ) -> x e. On )
15	14	ex 450	. . . . . 6 |- ( y e. On -> ( x e. y -> x e. On ) )
16	2, 15	syl6 35	. . . . 5 |- ( A C_ On -> ( y e. A -> ( x e. y -> x e. On ) ) )
17	16	rexlimdv 3030	. . . 4 |- ( A C_ On -> ( E. y e. A x e. y -> x e. On ) )
18	1, 17	syl5bi 232	. . 3 |- ( A C_ On -> ( x e. U. A -> x e. On ) )
19	18	ssrdv 3609	. 2 |- ( A C_ On -> U. A C_ On )
20		ordon 6982	. . 3 |- Ord On
21		trssord 5740	. . . 4 |- ( ( Tr U. A /\ U. A C_ On /\ Ord On ) -> Ord U. A )
22	21	3exp 1264	. . 3 |- ( Tr U. A -> ( U. A C_ On -> ( Ord On -> Ord U. A ) ) )
23	20, 22	mpii 46	. 2 |- ( Tr U. A -> ( U. A C_ On -> Ord U. A ) )
24	13, 19, 23	sylc 65	1 |- ( A C_ On -> Ord U. A )

Syntax hints:   -> wi 4   /\ wa 384   e. wcel 1990   A.wral 2912   E.wrex 2913   C_ wss 3574   U.cuni 4436   Tr wtr 4752   Ord word 5722   Oncon0 5723

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-8 1992  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-sep 4781  ax-nul 4789  ax-pr 4906  ax-un 6949

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3or 1038  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-eu 2474  df-mo 2475  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-ne 2795  df-ral 2917  df-rex 2918  df-rab 2921  df-v 3202  df-sbc 3436  df-dif 3577  df-un 3579  df-in 3581  df-ss 3588  df-pss 3590  df-nul 3916  df-if 4087  df-sn 4178  df-pr 4180  df-tp 4182  df-op 4184  df-uni 4437  df-br 4654  df-opab 4713  df-tr 4753  df-eprel 5029  df-po 5035  df-so 5036  df-fr 5073  df-we 5075  df-ord 5726  df-on 5727

This theorem is referenced by:  ssonuni  6986  ssonprc  6992  orduni  6994  onsucuni  7028  limuni3  7052  onfununi  7438  tfrlem8  7480  onssnum  8863  unialeph  8924  cfslbn  9089  hsmexlem1  9248  inaprc  9658  bdayimaon  31843  nosupbday  31851  noetalem3  31865  noetalem4  31866