Theorem 1oequni2o 38034

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 8450	. . 3 ⊢ 2o = suc 1o
2		2on 8463	. . . 4 ⊢ 2o ∈ On
3		2on0 8464	. . . 4 ⊢ 2o ≠ ∅
4		2onn 8624	. . . . 5 ⊢ 2o ∈ ω
5		nnlim 7872	. . . . 5 ⊢ (2o ∈ ω → ¬ Lim 2o)
6	4, 5	ax-mp 5	. . . 4 ⊢ ¬ Lim 2o
7		onsucuni3 38033	. . . 4 ⊢ ((2o ∈ On ∧ 2o ≠ ∅ ∧ ¬ Lim 2o) → 2o = suc ∪ 2o)
8	2, 3, 6, 7	mp3an 1490	. . 3 ⊢ 2o = suc ∪ 2o
9	1, 8	eqtr3i 2788	. 2 ⊢ suc 1o = suc ∪ 2o
10		1on 8462	. . 3 ⊢ 1o ∈ On
11		onuni 7783	. . . 4 ⊢ (2o ∈ On → ∪ 2o ∈ On)
12	2, 11	ax-mp 5	. . 3 ⊢ ∪ 2o ∈ On
13		suc11 6470	. . 3 ⊢ ((1o ∈ On ∧ ∪ 2o ∈ On) → (suc 1o = suc ∪ 2o ↔ 1o = ∪ 2o))
14	10, 12, 13	mp2an 704	. 2 ⊢ (suc 1o = suc ∪ 2o ↔ 1o = ∪ 2o)
15	9, 14	mpbi 233	1 ⊢ 1o = ∪ 2o

Syntax hints:  ¬ wn 3   ↔ wb 209   = wceq 1570   ∈ wcel 2143   ≠ wne 2958  ∅c0 4286  ∪ cuni 4872  Oncon0 6360  Lim wlim 6361  suc csuc 6362  ωcom 7858  1_oc1o 8442  2_oc2o 8443

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1825  ax-4 1839  ax-5 1940  ax-6 1997  ax-7 2038  ax-8 2145  ax-9 2153  ax-ext 2735  ax-sep 5257  ax-nul 5269  ax-pr 5404  ax-un 7732

This theorem depends on definitions:  df-bi 210  df-an 401  df-or 861  df-3or 1104  df-3an 1105  df-tru 1573  df-fal 1583  df-ex 1810  df-sb 2097  df-clab 2742  df-cleq 2755  df-clel 2838  df-ne 2959  df-ral 3080  df-rex 3090  df-rab 3417  df-v 3457  df-dif 3908  df-un 3910  df-in 3912  df-ss 3922  df-pss 3925  df-nul 4287  df-if 4488  df-pw 4564  df-sn 4590  df-pr 4592  df-op 4596  df-uni 4873  df-br 5110  df-opab 5174  df-tr 5219  df-eprel 5561  df-po 5569  df-so 5570  df-fr 5614  df-we 5616  df-ord 6363  df-on 6364  df-lim 6365  df-suc 6366  df-om 7859  df-1o 8449  df-2o 8450

This theorem is referenced by:  finxpreclem4  38060