Theorem 1oequni2o 37363

Description: The ordinal number 1_o is the predecessor of the ordinal number 2_o. (Contributed by ML, 19-Oct-2020.)

Assertion

Ref	Expression
1oequni2o	⊢ 1o = ∪ 2o

Proof of Theorem 1oequni2o

Step	Hyp	Ref	Expression
1		df-2o 8512	. . 3 ⊢ 2o = suc 1o
2		2on 8525	. . . 4 ⊢ 2o ∈ On
3		2on0 8527	. . . 4 ⊢ 2o ≠ ∅
4		2onn 8685	. . . . 5 ⊢ 2o ∈ ω
5		nnlim 7905	. . . . 5 ⊢ (2o ∈ ω → ¬ Lim 2o)
6	4, 5	ax-mp 5	. . . 4 ⊢ ¬ Lim 2o
7		onsucuni3 37362	. . . 4 ⊢ ((2o ∈ On ∧ 2o ≠ ∅ ∧ ¬ Lim 2o) → 2o = suc ∪ 2o)
8	2, 3, 6, 7	mp3an 1461	. . 3 ⊢ 2o = suc ∪ 2o
9	1, 8	eqtr3i 2766	. 2 ⊢ suc 1o = suc ∪ 2o
10		1on 8523	. . 3 ⊢ 1o ∈ On
11		onuni 7812	. . . 4 ⊢ (2o ∈ On → ∪ 2o ∈ On)
12	2, 11	ax-mp 5	. . 3 ⊢ ∪ 2o ∈ On
13		suc11 6496	. . 3 ⊢ ((1o ∈ On ∧ ∪ 2o ∈ On) → (suc 1o = suc ∪ 2o ↔ 1o = ∪ 2o))
14	10, 12, 13	mp2an 692	. 2 ⊢ (suc 1o = suc ∪ 2o ↔ 1o = ∪ 2o)
15	9, 14	mpbi 230	1 ⊢ 1o = ∪ 2o

Syntax hints:  ¬ wn 3   ↔ wb 206   = wceq 1538   ∈ wcel 2107   ≠ wne 2939  ∅c0 4340  ∪ cuni 4913  Oncon0 6389  Lim wlim 6390  suc csuc 6391  ωcom 7891  1_oc1o 8504  2_oc2o 8505

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1793  ax-4 1807  ax-5 1909  ax-6 1966  ax-7 2006  ax-8 2109  ax-9 2117  ax-ext 2707  ax-sep 5303  ax-nul 5313  ax-pr 5439  ax-un 7758

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1541  df-fal 1551  df-ex 1778  df-sb 2064  df-clab 2714  df-cleq 2728  df-clel 2815  df-ne 2940  df-ral 3061  df-rex 3070  df-rab 3435  df-v 3481  df-dif 3967  df-un 3969  df-in 3971  df-ss 3981  df-pss 3984  df-nul 4341  df-if 4533  df-pw 4608  df-sn 4633  df-pr 4635  df-op 4639  df-uni 4914  df-br 5150  df-opab 5212  df-tr 5267  df-eprel 5590  df-po 5598  df-so 5599  df-fr 5642  df-we 5644  df-ord 6392  df-on 6393  df-lim 6394  df-suc 6395  df-om 7892  df-1o 8511  df-2o 8512

This theorem is referenced by:  finxpreclem4  37389