Theorem tfindsg 7707

Description: Transfinite Induction (inference schema), using implicit substitutions. The first four hypotheses establish the substitutions we need. The last three are the basis, the induction step for successors, and the induction step for limit ordinals. The basis of this version is an arbitrary ordinal 𝐵 instead of zero. Remark in [TakeutiZaring] p. 57. (Contributed by NM, 5-Mar-2004.)

Hypotheses

Ref	Expression
tfindsg.1	⊢ (𝑥 = 𝐵 → (𝜑 ↔ 𝜓))
tfindsg.2	⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜒))
tfindsg.3	⊢ (𝑥 = suc 𝑦 → (𝜑 ↔ 𝜃))
tfindsg.4	⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜏))
tfindsg.5	⊢ (𝐵 ∈ On → 𝜓)
tfindsg.6	⊢ (((𝑦 ∈ On ∧ 𝐵 ∈ On) ∧ 𝐵 ⊆ 𝑦) → (𝜒 → 𝜃))
tfindsg.7	⊢ (((Lim 𝑥 ∧ 𝐵 ∈ On) ∧ 𝐵 ⊆ 𝑥) → (∀𝑦 ∈ 𝑥 (𝐵 ⊆ 𝑦 → 𝜒) → 𝜑))

Assertion

Ref	Expression
tfindsg	⊢ (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ 𝐵 ⊆ 𝐴) → 𝜏)

Distinct variable groups:   𝑥,𝐴   𝑥,𝑦,𝐵   𝜒,𝑥   𝜃,𝑥   𝜏,𝑥   𝜑,𝑦

Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑥,𝑦)   𝜒(𝑦)   𝜃(𝑦)   𝜏(𝑦)   𝐴(𝑦)

Proof of Theorem tfindsg

Step	Hyp	Ref	Expression
1		sseq2 3948	. . . . . . 7 ⊢ (𝑥 = ∅ → (𝐵 ⊆ 𝑥 ↔ 𝐵 ⊆ ∅))
2	1	adantl 482	. . . . . 6 ⊢ ((𝐵 = ∅ ∧ 𝑥 = ∅) → (𝐵 ⊆ 𝑥 ↔ 𝐵 ⊆ ∅))
3		eqeq2 2750	. . . . . . . 8 ⊢ (𝐵 = ∅ → (𝑥 = 𝐵 ↔ 𝑥 = ∅))
4		tfindsg.1	. . . . . . . 8 ⊢ (𝑥 = 𝐵 → (𝜑 ↔ 𝜓))
5	3, 4	syl6bir 253	. . . . . . 7 ⊢ (𝐵 = ∅ → (𝑥 = ∅ → (𝜑 ↔ 𝜓)))
6	5	imp 407	. . . . . 6 ⊢ ((𝐵 = ∅ ∧ 𝑥 = ∅) → (𝜑 ↔ 𝜓))
7	2, 6	imbi12d 345	. . . . 5 ⊢ ((𝐵 = ∅ ∧ 𝑥 = ∅) → ((𝐵 ⊆ 𝑥 → 𝜑) ↔ (𝐵 ⊆ ∅ → 𝜓)))
8	1	imbi1d 342	. . . . . 6 ⊢ (𝑥 = ∅ → ((𝐵 ⊆ 𝑥 → 𝜑) ↔ (𝐵 ⊆ ∅ → 𝜑)))
9		ss0 4334	. . . . . . . . 9 ⊢ (𝐵 ⊆ ∅ → 𝐵 = ∅)
10	9	con3i 154	. . . . . . . 8 ⊢ (¬ 𝐵 = ∅ → ¬ 𝐵 ⊆ ∅)
11	10	pm2.21d 121	. . . . . . 7 ⊢ (¬ 𝐵 = ∅ → (𝐵 ⊆ ∅ → (𝜑 ↔ 𝜓)))
12	11	pm5.74d 272	. . . . . 6 ⊢ (¬ 𝐵 = ∅ → ((𝐵 ⊆ ∅ → 𝜑) ↔ (𝐵 ⊆ ∅ → 𝜓)))
13	8, 12	sylan9bbr 511	. . . . 5 ⊢ ((¬ 𝐵 = ∅ ∧ 𝑥 = ∅) → ((𝐵 ⊆ 𝑥 → 𝜑) ↔ (𝐵 ⊆ ∅ → 𝜓)))
14	7, 13	pm2.61ian 809	. . . 4 ⊢ (𝑥 = ∅ → ((𝐵 ⊆ 𝑥 → 𝜑) ↔ (𝐵 ⊆ ∅ → 𝜓)))
15	14	imbi2d 341	. . 3 ⊢ (𝑥 = ∅ → ((𝐵 ∈ On → (𝐵 ⊆ 𝑥 → 𝜑)) ↔ (𝐵 ∈ On → (𝐵 ⊆ ∅ → 𝜓))))
16		sseq2 3948	. . . . 5 ⊢ (𝑥 = 𝑦 → (𝐵 ⊆ 𝑥 ↔ 𝐵 ⊆ 𝑦))
17		tfindsg.2	. . . . 5 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜒))
18	16, 17	imbi12d 345	. . . 4 ⊢ (𝑥 = 𝑦 → ((𝐵 ⊆ 𝑥 → 𝜑) ↔ (𝐵 ⊆ 𝑦 → 𝜒)))
19	18	imbi2d 341	. . 3 ⊢ (𝑥 = 𝑦 → ((𝐵 ∈ On → (𝐵 ⊆ 𝑥 → 𝜑)) ↔ (𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒))))
20		sseq2 3948	. . . . 5 ⊢ (𝑥 = suc 𝑦 → (𝐵 ⊆ 𝑥 ↔ 𝐵 ⊆ suc 𝑦))
21		tfindsg.3	. . . . 5 ⊢ (𝑥 = suc 𝑦 → (𝜑 ↔ 𝜃))
22	20, 21	imbi12d 345	. . . 4 ⊢ (𝑥 = suc 𝑦 → ((𝐵 ⊆ 𝑥 → 𝜑) ↔ (𝐵 ⊆ suc 𝑦 → 𝜃)))
23	22	imbi2d 341	. . 3 ⊢ (𝑥 = suc 𝑦 → ((𝐵 ∈ On → (𝐵 ⊆ 𝑥 → 𝜑)) ↔ (𝐵 ∈ On → (𝐵 ⊆ suc 𝑦 → 𝜃))))
24		sseq2 3948	. . . . 5 ⊢ (𝑥 = 𝐴 → (𝐵 ⊆ 𝑥 ↔ 𝐵 ⊆ 𝐴))
25		tfindsg.4	. . . . 5 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜏))
26	24, 25	imbi12d 345	. . . 4 ⊢ (𝑥 = 𝐴 → ((𝐵 ⊆ 𝑥 → 𝜑) ↔ (𝐵 ⊆ 𝐴 → 𝜏)))
27	26	imbi2d 341	. . 3 ⊢ (𝑥 = 𝐴 → ((𝐵 ∈ On → (𝐵 ⊆ 𝑥 → 𝜑)) ↔ (𝐵 ∈ On → (𝐵 ⊆ 𝐴 → 𝜏))))
28		tfindsg.5	. . . 4 ⊢ (𝐵 ∈ On → 𝜓)
29	28	a1d 25	. . 3 ⊢ (𝐵 ∈ On → (𝐵 ⊆ ∅ → 𝜓))
30		vex 3435	. . . . . . . . . . . . . 14 ⊢ 𝑦 ∈ V
31	30	sucex 7656	. . . . . . . . . . . . 13 ⊢ suc 𝑦 ∈ V
32	31	eqvinc 3580	. . . . . . . . . . . 12 ⊢ (suc 𝑦 = 𝐵 ↔ ∃𝑥(𝑥 = suc 𝑦 ∧ 𝑥 = 𝐵))
33	28, 4	syl5ibr 245	. . . . . . . . . . . . . 14 ⊢ (𝑥 = 𝐵 → (𝐵 ∈ On → 𝜑))
34	21	biimpd 228	. . . . . . . . . . . . . 14 ⊢ (𝑥 = suc 𝑦 → (𝜑 → 𝜃))
35	33, 34	sylan9r 509	. . . . . . . . . . . . 13 ⊢ ((𝑥 = suc 𝑦 ∧ 𝑥 = 𝐵) → (𝐵 ∈ On → 𝜃))
36	35	exlimiv 1933	. . . . . . . . . . . 12 ⊢ (∃𝑥(𝑥 = suc 𝑦 ∧ 𝑥 = 𝐵) → (𝐵 ∈ On → 𝜃))
37	32, 36	sylbi 216	. . . . . . . . . . 11 ⊢ (suc 𝑦 = 𝐵 → (𝐵 ∈ On → 𝜃))
38	37	eqcoms 2746	. . . . . . . . . 10 ⊢ (𝐵 = suc 𝑦 → (𝐵 ∈ On → 𝜃))
39	38	imim2i 16	. . . . . . . . 9 ⊢ ((𝐵 ⊆ suc 𝑦 → 𝐵 = suc 𝑦) → (𝐵 ⊆ suc 𝑦 → (𝐵 ∈ On → 𝜃)))
40	39	a1d 25	. . . . . . . 8 ⊢ ((𝐵 ⊆ suc 𝑦 → 𝐵 = suc 𝑦) → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ suc 𝑦 → (𝐵 ∈ On → 𝜃))))
41	40	com4r 94	. . . . . . 7 ⊢ (𝐵 ∈ On → ((𝐵 ⊆ suc 𝑦 → 𝐵 = suc 𝑦) → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ suc 𝑦 → 𝜃))))
42	41	adantl 482	. . . . . 6 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → ((𝐵 ⊆ suc 𝑦 → 𝐵 = suc 𝑦) → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ suc 𝑦 → 𝜃))))
43		df-ne 2944	. . . . . . . . 9 ⊢ (𝐵 ≠ suc 𝑦 ↔ ¬ 𝐵 = suc 𝑦)
44	43	anbi2i 623	. . . . . . . 8 ⊢ ((𝐵 ⊆ suc 𝑦 ∧ 𝐵 ≠ suc 𝑦) ↔ (𝐵 ⊆ suc 𝑦 ∧ ¬ 𝐵 = suc 𝑦))
45		annim 404	. . . . . . . 8 ⊢ ((𝐵 ⊆ suc 𝑦 ∧ ¬ 𝐵 = suc 𝑦) ↔ ¬ (𝐵 ⊆ suc 𝑦 → 𝐵 = suc 𝑦))
46	44, 45	bitri 274	. . . . . . 7 ⊢ ((𝐵 ⊆ suc 𝑦 ∧ 𝐵 ≠ suc 𝑦) ↔ ¬ (𝐵 ⊆ suc 𝑦 → 𝐵 = suc 𝑦))
47		onsssuc 6355	. . . . . . . . . 10 ⊢ ((𝐵 ∈ On ∧ 𝑦 ∈ On) → (𝐵 ⊆ 𝑦 ↔ 𝐵 ∈ suc 𝑦))
48		suceloni 7659	. . . . . . . . . . 11 ⊢ (𝑦 ∈ On → suc 𝑦 ∈ On)
49		onelpss 6308	. . . . . . . . . . 11 ⊢ ((𝐵 ∈ On ∧ suc 𝑦 ∈ On) → (𝐵 ∈ suc 𝑦 ↔ (𝐵 ⊆ suc 𝑦 ∧ 𝐵 ≠ suc 𝑦)))
50	48, 49	sylan2 593	. . . . . . . . . 10 ⊢ ((𝐵 ∈ On ∧ 𝑦 ∈ On) → (𝐵 ∈ suc 𝑦 ↔ (𝐵 ⊆ suc 𝑦 ∧ 𝐵 ≠ suc 𝑦)))
51	47, 50	bitrd 278	. . . . . . . . 9 ⊢ ((𝐵 ∈ On ∧ 𝑦 ∈ On) → (𝐵 ⊆ 𝑦 ↔ (𝐵 ⊆ suc 𝑦 ∧ 𝐵 ≠ suc 𝑦)))
52	51	ancoms 459	. . . . . . . 8 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → (𝐵 ⊆ 𝑦 ↔ (𝐵 ⊆ suc 𝑦 ∧ 𝐵 ≠ suc 𝑦)))
53		tfindsg.6	. . . . . . . . . . . 12 ⊢ (((𝑦 ∈ On ∧ 𝐵 ∈ On) ∧ 𝐵 ⊆ 𝑦) → (𝜒 → 𝜃))
54	53	ex 413	. . . . . . . . . . 11 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → (𝐵 ⊆ 𝑦 → (𝜒 → 𝜃)))
55	54	a1ddd 80	. . . . . . . . . 10 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → (𝐵 ⊆ 𝑦 → (𝜒 → (𝐵 ⊆ suc 𝑦 → 𝜃))))
56	55	a2d 29	. . . . . . . . 9 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ 𝑦 → (𝐵 ⊆ suc 𝑦 → 𝜃))))
57	56	com23 86	. . . . . . . 8 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → (𝐵 ⊆ 𝑦 → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ suc 𝑦 → 𝜃))))
58	52, 57	sylbird 259	. . . . . . 7 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → ((𝐵 ⊆ suc 𝑦 ∧ 𝐵 ≠ suc 𝑦) → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ suc 𝑦 → 𝜃))))
59	46, 58	syl5bir 242	. . . . . 6 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → (¬ (𝐵 ⊆ suc 𝑦 → 𝐵 = suc 𝑦) → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ suc 𝑦 → 𝜃))))
60	42, 59	pm2.61d 179	. . . . 5 ⊢ ((𝑦 ∈ On ∧ 𝐵 ∈ On) → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ suc 𝑦 → 𝜃)))
61	60	ex 413	. . . 4 ⊢ (𝑦 ∈ On → (𝐵 ∈ On → ((𝐵 ⊆ 𝑦 → 𝜒) → (𝐵 ⊆ suc 𝑦 → 𝜃))))
62	61	a2d 29	. . 3 ⊢ (𝑦 ∈ On → ((𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒)) → (𝐵 ∈ On → (𝐵 ⊆ suc 𝑦 → 𝜃))))
63		pm2.27 42	. . . . . . . . 9 ⊢ (𝐵 ∈ On → ((𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒)) → (𝐵 ⊆ 𝑦 → 𝜒)))
64	63	ralimdv 3109	. . . . . . . 8 ⊢ (𝐵 ∈ On → (∀𝑦 ∈ 𝑥 (𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒)) → ∀𝑦 ∈ 𝑥 (𝐵 ⊆ 𝑦 → 𝜒)))
65	64	ad2antlr 724	. . . . . . 7 ⊢ (((Lim 𝑥 ∧ 𝐵 ∈ On) ∧ 𝐵 ⊆ 𝑥) → (∀𝑦 ∈ 𝑥 (𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒)) → ∀𝑦 ∈ 𝑥 (𝐵 ⊆ 𝑦 → 𝜒)))
66		tfindsg.7	. . . . . . 7 ⊢ (((Lim 𝑥 ∧ 𝐵 ∈ On) ∧ 𝐵 ⊆ 𝑥) → (∀𝑦 ∈ 𝑥 (𝐵 ⊆ 𝑦 → 𝜒) → 𝜑))
67	65, 66	syld 47	. . . . . 6 ⊢ (((Lim 𝑥 ∧ 𝐵 ∈ On) ∧ 𝐵 ⊆ 𝑥) → (∀𝑦 ∈ 𝑥 (𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒)) → 𝜑))
68	67	exp31 420	. . . . 5 ⊢ (Lim 𝑥 → (𝐵 ∈ On → (𝐵 ⊆ 𝑥 → (∀𝑦 ∈ 𝑥 (𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒)) → 𝜑))))
69	68	com3l 89	. . . 4 ⊢ (𝐵 ∈ On → (𝐵 ⊆ 𝑥 → (Lim 𝑥 → (∀𝑦 ∈ 𝑥 (𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒)) → 𝜑))))
70	69	com4t 93	. . 3 ⊢ (Lim 𝑥 → (∀𝑦 ∈ 𝑥 (𝐵 ∈ On → (𝐵 ⊆ 𝑦 → 𝜒)) → (𝐵 ∈ On → (𝐵 ⊆ 𝑥 → 𝜑))))
71	15, 19, 23, 27, 29, 62, 70	tfinds 7706	. 2 ⊢ (𝐴 ∈ On → (𝐵 ∈ On → (𝐵 ⊆ 𝐴 → 𝜏)))
72	71	imp31 418	1 ⊢ (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ 𝐵 ⊆ 𝐴) → 𝜏)

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 205   ∧ wa 396   = wceq 1539  ∃wex 1782   ∈ wcel 2106   ≠ wne 2943  ∀wral 3064   ⊆ wss 3888  ∅c0 4258  Oncon0 6268  Lim wlim 6269  suc csuc 6270

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1913  ax-6 1971  ax-7 2011  ax-8 2108  ax-9 2116  ax-10 2137  ax-11 2154  ax-12 2171  ax-ext 2709  ax-sep 5225  ax-nul 5232  ax-pr 5354  ax-un 7588

This theorem depends on definitions:  df-bi 206  df-an 397  df-or 845  df-3or 1087  df-3an 1088  df-tru 1542  df-fal 1552  df-ex 1783  df-nf 1787  df-sb 2068  df-clab 2716  df-cleq 2730  df-clel 2816  df-nfc 2889  df-ne 2944  df-ral 3069  df-rex 3070  df-rab 3073  df-v 3433  df-dif 3891  df-un 3893  df-in 3895  df-ss 3905  df-pss 3907  df-nul 4259  df-if 4462  df-pw 4537  df-sn 4564  df-pr 4566  df-op 4570  df-uni 4842  df-br 5077  df-opab 5139  df-tr 5194  df-eprel 5497  df-po 5505  df-so 5506  df-fr 5546  df-we 5548  df-ord 6271  df-on 6272  df-lim 6273  df-suc 6274

This theorem is referenced by:  tfindsg2  7708  oaordi  8375  infensuc  8940  r1ordg  9534