Theorem bj-nn0sucALT 13347

Description: Alternate proof of bj-nn0suc 13333, also constructive but from ax-inf2 13345, hence requiring ax-bdsetind 13337. (Contributed by BJ, 8-Dec-2019.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
bj-nn0sucALT	⊢ (𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))

Distinct variable group:   𝑥,𝐴

Proof of Theorem bj-nn0sucALT

Dummy variables 𝑎 𝑦 𝑧 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		ax-inf2 13345	. . 3 ⊢ ∃𝑎∀𝑦(𝑦 ∈ 𝑎 ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧))
2		vex 2692	. . . . 5 ⊢ 𝑎 ∈ V
3		bdcv 13217	. . . . . 6 ⊢ BOUNDED 𝑎
4	3	bj-inf2vn 13343	. . . . 5 ⊢ (𝑎 ∈ V → (∀𝑦(𝑦 ∈ 𝑎 ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧)) → 𝑎 = ω))
5	2, 4	ax-mp 5	. . . 4 ⊢ (∀𝑦(𝑦 ∈ 𝑎 ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧)) → 𝑎 = ω)
6		eleq2 2204	. . . . . . 7 ⊢ (𝑎 = ω → (𝑦 ∈ 𝑎 ↔ 𝑦 ∈ ω))
7		rexeq 2630	. . . . . . . 8 ⊢ (𝑎 = ω → (∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧 ↔ ∃𝑧 ∈ ω 𝑦 = suc 𝑧))
8	7	orbi2d 780	. . . . . . 7 ⊢ (𝑎 = ω → ((𝑦 = ∅ ∨ ∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧) ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧)))
9	6, 8	bibi12d 234	. . . . . 6 ⊢ (𝑎 = ω → ((𝑦 ∈ 𝑎 ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧)) ↔ (𝑦 ∈ ω ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧))))
10	9	albidv 1797	. . . . 5 ⊢ (𝑎 = ω → (∀𝑦(𝑦 ∈ 𝑎 ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧)) ↔ ∀𝑦(𝑦 ∈ ω ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧))))
11		nfcv 2282	. . . . . . . 8 ⊢ Ⅎ𝑦𝐴
12		nfv 1509	. . . . . . . 8 ⊢ Ⅎ𝑦(𝐴 ∈ ω → (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))
13		eleq1 2203	. . . . . . . . . 10 ⊢ (𝑦 = 𝐴 → (𝑦 ∈ ω ↔ 𝐴 ∈ ω))
14		eqeq1 2147	. . . . . . . . . . 11 ⊢ (𝑦 = 𝐴 → (𝑦 = ∅ ↔ 𝐴 = ∅))
15		suceq 4332	. . . . . . . . . . . . . 14 ⊢ (𝑧 = 𝑥 → suc 𝑧 = suc 𝑥)
16	15	eqeq2d 2152	. . . . . . . . . . . . 13 ⊢ (𝑧 = 𝑥 → (𝑦 = suc 𝑧 ↔ 𝑦 = suc 𝑥))
17	16	cbvrexv 2658	. . . . . . . . . . . 12 ⊢ (∃𝑧 ∈ ω 𝑦 = suc 𝑧 ↔ ∃𝑥 ∈ ω 𝑦 = suc 𝑥)
18		eqeq1 2147	. . . . . . . . . . . . 13 ⊢ (𝑦 = 𝐴 → (𝑦 = suc 𝑥 ↔ 𝐴 = suc 𝑥))
19	18	rexbidv 2439	. . . . . . . . . . . 12 ⊢ (𝑦 = 𝐴 → (∃𝑥 ∈ ω 𝑦 = suc 𝑥 ↔ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))
20	17, 19	syl5bb 191	. . . . . . . . . . 11 ⊢ (𝑦 = 𝐴 → (∃𝑧 ∈ ω 𝑦 = suc 𝑧 ↔ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))
21	14, 20	orbi12d 783	. . . . . . . . . 10 ⊢ (𝑦 = 𝐴 → ((𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧) ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥)))
22	13, 21	bibi12d 234	. . . . . . . . 9 ⊢ (𝑦 = 𝐴 → ((𝑦 ∈ ω ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧)) ↔ (𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))))
23		bi1 117	. . . . . . . . 9 ⊢ ((𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥)) → (𝐴 ∈ ω → (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥)))
24	22, 23	syl6bi 162	. . . . . . . 8 ⊢ (𝑦 = 𝐴 → ((𝑦 ∈ ω ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧)) → (𝐴 ∈ ω → (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))))
25	11, 12, 24	spcimgf 2769	. . . . . . 7 ⊢ (𝐴 ∈ ω → (∀𝑦(𝑦 ∈ ω ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧)) → (𝐴 ∈ ω → (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))))
26	25	pm2.43b 52	. . . . . 6 ⊢ (∀𝑦(𝑦 ∈ ω ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧)) → (𝐴 ∈ ω → (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥)))
27		peano1 4516	. . . . . . . 8 ⊢ ∅ ∈ ω
28		eleq1 2203	. . . . . . . 8 ⊢ (𝐴 = ∅ → (𝐴 ∈ ω ↔ ∅ ∈ ω))
29	27, 28	mpbiri 167	. . . . . . 7 ⊢ (𝐴 = ∅ → 𝐴 ∈ ω)
30		bj-peano2 13308	. . . . . . . . 9 ⊢ (𝑥 ∈ ω → suc 𝑥 ∈ ω)
31		eleq1a 2212	. . . . . . . . . 10 ⊢ (suc 𝑥 ∈ ω → (𝐴 = suc 𝑥 → 𝐴 ∈ ω))
32	31	imp 123	. . . . . . . . 9 ⊢ ((suc 𝑥 ∈ ω ∧ 𝐴 = suc 𝑥) → 𝐴 ∈ ω)
33	30, 32	sylan 281	. . . . . . . 8 ⊢ ((𝑥 ∈ ω ∧ 𝐴 = suc 𝑥) → 𝐴 ∈ ω)
34	33	rexlimiva 2547	. . . . . . 7 ⊢ (∃𝑥 ∈ ω 𝐴 = suc 𝑥 → 𝐴 ∈ ω)
35	29, 34	jaoi 706	. . . . . 6 ⊢ ((𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥) → 𝐴 ∈ ω)
36	26, 35	impbid1 141	. . . . 5 ⊢ (∀𝑦(𝑦 ∈ ω ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ ω 𝑦 = suc 𝑧)) → (𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥)))
37	10, 36	syl6bi 162	. . . 4 ⊢ (𝑎 = ω → (∀𝑦(𝑦 ∈ 𝑎 ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧)) → (𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))))
38	5, 37	mpcom 36	. . 3 ⊢ (∀𝑦(𝑦 ∈ 𝑎 ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ 𝑎 𝑦 = suc 𝑧)) → (𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥)))
39	1, 38	eximii 1582	. 2 ⊢ ∃𝑎(𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))
40		bj-ex 13140	. 2 ⊢ (∃𝑎(𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥)) → (𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥)))
41	39, 40	ax-mp 5	1 ⊢ (𝐴 ∈ ω ↔ (𝐴 = ∅ ∨ ∃𝑥 ∈ ω 𝐴 = suc 𝑥))

Syntax hints:   → wi 4   ↔ wb 104   ∨ wo 698  ∀wal 1330   = wceq 1332  ∃wex 1469   ∈ wcel 1481  ∃wrex 2418  Vcvv 2689  ∅c0 3368  suc csuc 4295  ωcom 4512

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-in1 604  ax-in2 605  ax-io 699  ax-5 1424  ax-7 1425  ax-gen 1426  ax-ie1 1470  ax-ie2 1471  ax-8 1483  ax-10 1484  ax-11 1485  ax-i12 1486  ax-bndl 1487  ax-4 1488  ax-13 1492  ax-14 1493  ax-17 1507  ax-i9 1511  ax-ial 1515  ax-i5r 1516  ax-ext 2122  ax-nul 4062  ax-pr 4139  ax-un 4363  ax-bd0 13182  ax-bdim 13183  ax-bdor 13185  ax-bdex 13188  ax-bdeq 13189  ax-bdel 13190  ax-bdsb 13191  ax-bdsep 13253  ax-bdsetind 13337  ax-inf2 13345

This theorem depends on definitions:  df-bi 116  df-tru 1335  df-nf 1438  df-sb 1737  df-clab 2127  df-cleq 2133  df-clel 2136  df-nfc 2271  df-ral 2422  df-rex 2423  df-rab 2426  df-v 2691  df-dif 3078  df-un 3080  df-in 3082  df-ss 3089  df-nul 3369  df-sn 3538  df-pr 3539  df-uni 3745  df-int 3780  df-suc 4301  df-iom 4513  df-bdc 13210  df-bj-ind 13296

This theorem is referenced by: (None)