Theorem onuniorsuci 7554

Description: An ordinal number is either its own union (if zero or a limit ordinal) or the successor of its union. (Contributed by NM, 13-Jun-1994.)

Hypothesis

Ref	Expression
onssi.1	⊢ 𝐴 ∈ On

Assertion

Ref	Expression
onuniorsuci	⊢ (𝐴 = ∪ 𝐴 ∨ 𝐴 = suc ∪ 𝐴)

Proof of Theorem onuniorsuci

Step	Hyp	Ref	Expression
1		onssi.1	. . 3 ⊢ 𝐴 ∈ On
2	1	onordi 6295	. 2 ⊢ Ord 𝐴
3		orduniorsuc 7545	. 2 ⊢ (Ord 𝐴 → (𝐴 = ∪ 𝐴 ∨ 𝐴 = suc ∪ 𝐴))
4	2, 3	ax-mp 5	1 ⊢ (𝐴 = ∪ 𝐴 ∨ 𝐴 = suc ∪ 𝐴)

Syntax hints:   ∨ wo 843   = wceq 1537   ∈ wcel 2114  ∪ cuni 4838  Ord word 6190  Oncon0 6191  suc csuc 6193

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2116  ax-9 2124  ax-10 2145  ax-11 2161  ax-12 2177  ax-ext 2793  ax-sep 5203  ax-nul 5210  ax-pr 5330  ax-un 7461

This theorem depends on definitions:  df-bi 209  df-an 399  df-or 844  df-3or 1084  df-3an 1085  df-tru 1540  df-ex 1781  df-nf 1785  df-sb 2070  df-mo 2622  df-eu 2654  df-clab 2800  df-cleq 2814  df-clel 2893  df-nfc 2963  df-ne 3017  df-ral 3143  df-rex 3144  df-rab 3147  df-v 3496  df-sbc 3773  df-dif 3939  df-un 3941  df-in 3943  df-ss 3952  df-pss 3954  df-nul 4292  df-if 4468  df-sn 4568  df-pr 4570  df-tp 4572  df-op 4574  df-uni 4839  df-br 5067  df-opab 5129  df-tr 5173  df-eprel 5465  df-po 5474  df-so 5475  df-fr 5514  df-we 5516  df-ord 6194  df-on 6195  df-suc 6197

This theorem is referenced by:  onuninsuci  7555