Theorem ordon 4463

Description: The class of all ordinal numbers is ordinal. Proposition 7.12 of [TakeutiZaring] p. 38, but without using the Axiom of Regularity. (Contributed by NM, 17-May-1994.)

Assertion

Ref	Expression
ordon	|- Ord On

Proof of Theorem ordon

Step	Hyp	Ref	Expression
1		tron 4360	. 2 |- Tr On
2		df-on 4346	. . . . 5 |- On = { x | Ord x }
3	2	abeq2i 2277	. . . 4 |- ( x e. On <-> Ord x )
4		ordtr 4356	. . . 4 |- ( Ord x -> Tr x )
5	3, 4	sylbi 120	. . 3 |- ( x e. On -> Tr x )
6	5	rgen 2519	. 2 |- A. x e. On Tr x
7		dford3 4345	. 2 |- ( Ord On <-> ( Tr On /\ A. x e. On Tr x ) )
8	1, 6, 7	mpbir2an 932	1 |- Ord On

Syntax hints:   e. wcel 2136   A.wral 2444   Tr wtr 4080   Ord word 4340   Oncon0 4341

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 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-bndl 1497  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522  ax-i5r 1523  ax-ext 2147

This theorem depends on definitions:  df-bi 116  df-3an 970  df-tru 1346  df-nf 1449  df-sb 1751  df-clab 2152  df-cleq 2158  df-clel 2161  df-nfc 2297  df-ral 2449  df-rex 2450  df-v 2728  df-in 3122  df-ss 3129  df-uni 3790  df-tr 4081  df-iord 4344  df-on 4346

This theorem is referenced by:  ssorduni  4464  limon  4490  onprc  4529  tfri1dALT  6319  rdgon  6354