Theorem onirri 6046

Description: An ordinal number is not a member of itself. Theorem 7M(c) of [Enderton] p. 192. (Contributed by NM, 11-Jun-1994.)

Hypothesis

Ref	Expression
on.1	⊢ 𝐴 ∈ On

Assertion

Ref	Expression
onirri	⊢ ¬ 𝐴 ∈ 𝐴

Proof of Theorem onirri

Step	Hyp	Ref	Expression
1		on.1	. . 3 ⊢ 𝐴 ∈ On
2	1	onordi 6044	. 2 ⊢ Ord 𝐴
3		ordirr 5958	. 2 ⊢ (Ord 𝐴 → ¬ 𝐴 ∈ 𝐴)
4	2, 3	ax-mp 5	1 ⊢ ¬ 𝐴 ∈ 𝐴

Syntax hints:  ¬ wn 3   ∈ wcel 2157  Ord word 5939  Oncon0 5940

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1891  ax-4 1905  ax-5 2006  ax-6 2072  ax-7 2107  ax-9 2166  ax-10 2185  ax-11 2200  ax-12 2213  ax-13 2377  ax-ext 2776  ax-sep 4974  ax-nul 4982  ax-pr 5096

This theorem depends on definitions:  df-bi 199  df-an 386  df-or 875  df-3an 1110  df-tru 1657  df-ex 1876  df-nf 1880  df-sb 2065  df-mo 2591  df-eu 2609  df-clab 2785  df-cleq 2791  df-clel 2794  df-nfc 2929  df-ne 2971  df-ral 3093  df-rex 3094  df-rab 3097  df-v 3386  df-sbc 3633  df-dif 3771  df-un 3773  df-in 3775  df-ss 3782  df-nul 4115  df-if 4277  df-sn 4368  df-pr 4370  df-op 4374  df-uni 4628  df-br 4843  df-opab 4905  df-tr 4945  df-eprel 5224  df-po 5232  df-so 5233  df-fr 5270  df-we 5272  df-ord 5943  df-on 5944

This theorem is referenced by:  onssnel2i  6050  onuninsuci  7273  oelim2  7914  omopthlem2  7975  harndom  8710  wfelirr  8937  carduni  9092  pm54.43  9111  alephle  9196  alephfp  9216  pwxpndom2  9774  onsucsuccmpi  32943  onint1  32949  finxpreclem5  33723  wepwsolem  38386