Theorem setindtr 43779

Description: Set induction for sets contained in a transitive set. If we are allowed to assume Infinity, then all sets have a transitive closure and this reduces to setind 9712; however, this version is useful without Infinity. (Contributed by Stefan O'Rear, 28-Oct-2014.)

Assertion

Ref	Expression
setindtr	⊢ (∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴) → (∃𝑦(Tr 𝑦 ∧ 𝐵 ∈ 𝑦) → 𝐵 ∈ 𝐴))

Distinct variable groups:   𝑥,𝑦,𝐴   𝑥,𝐵,𝑦

Proof of Theorem setindtr

Step	Hyp	Ref	Expression
1		nfv 1944	. . . . . . . . . . 11 ⊢ Ⅎ𝑥Tr 𝑦
2		nfa1 2186	. . . . . . . . . . 11 ⊢ Ⅎ𝑥∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)
3	1, 2	nfan 1929	. . . . . . . . . 10 ⊢ Ⅎ𝑥(Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴))
4		eldifn 4086	. . . . . . . . . . . . . 14 ⊢ (𝑥 ∈ (𝑦 ∖ 𝐴) → ¬ 𝑥 ∈ 𝐴)
5	4	adantl 486	. . . . . . . . . . . . 13 ⊢ (((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → ¬ 𝑥 ∈ 𝐴)
6		trss 5228	. . . . . . . . . . . . . . . . . 18 ⊢ (Tr 𝑦 → (𝑥 ∈ 𝑦 → 𝑥 ⊆ 𝑦))
7		eldifi 4085	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑥 ∈ (𝑦 ∖ 𝐴) → 𝑥 ∈ 𝑦)
8	6, 7	impel 514	. . . . . . . . . . . . . . . . 17 ⊢ ((Tr 𝑦 ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → 𝑥 ⊆ 𝑦)
9		dfss2 3923	. . . . . . . . . . . . . . . . 17 ⊢ (𝑥 ⊆ 𝑦 ↔ (𝑥 ∩ 𝑦) = 𝑥)
10	8, 9	sylib 221	. . . . . . . . . . . . . . . 16 ⊢ ((Tr 𝑦 ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → (𝑥 ∩ 𝑦) = 𝑥)
11	10	adantlr 727	. . . . . . . . . . . . . . 15 ⊢ (((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → (𝑥 ∩ 𝑦) = 𝑥)
12	11	sseq1d 3968	. . . . . . . . . . . . . 14 ⊢ (((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → ((𝑥 ∩ 𝑦) ⊆ 𝐴 ↔ 𝑥 ⊆ 𝐴))
13		sp 2219	. . . . . . . . . . . . . . 15 ⊢ (∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴) → (𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴))
14	13	ad2antlr 739	. . . . . . . . . . . . . 14 ⊢ (((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → (𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴))
15	12, 14	sylbid 243	. . . . . . . . . . . . 13 ⊢ (((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → ((𝑥 ∩ 𝑦) ⊆ 𝐴 → 𝑥 ∈ 𝐴))
16	5, 15	mtod 201	. . . . . . . . . . . 12 ⊢ (((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → ¬ (𝑥 ∩ 𝑦) ⊆ 𝐴)
17		inssdif0 4329	. . . . . . . . . . . 12 ⊢ ((𝑥 ∩ 𝑦) ⊆ 𝐴 ↔ (𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅)
18	16, 17	sylnib 331	. . . . . . . . . . 11 ⊢ (((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) ∧ 𝑥 ∈ (𝑦 ∖ 𝐴)) → ¬ (𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅)
19	18	ex 417	. . . . . . . . . 10 ⊢ ((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) → (𝑥 ∈ (𝑦 ∖ 𝐴) → ¬ (𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅))
20	3, 19	ralrimi 3263	. . . . . . . . 9 ⊢ ((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) → ∀𝑥 ∈ (𝑦 ∖ 𝐴) ¬ (𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅)
21		ralnex 3091	. . . . . . . . 9 ⊢ (∀𝑥 ∈ (𝑦 ∖ 𝐴) ¬ (𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅ ↔ ¬ ∃𝑥 ∈ (𝑦 ∖ 𝐴)(𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅)
22	20, 21	sylib 221	. . . . . . . 8 ⊢ ((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) → ¬ ∃𝑥 ∈ (𝑦 ∖ 𝐴)(𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅)
23		vex 3459	. . . . . . . . . . 11 ⊢ 𝑦 ∈ V
24	23	difexi 5301	. . . . . . . . . 10 ⊢ (𝑦 ∖ 𝐴) ∈ V
25		zfreg 9554	. . . . . . . . . 10 ⊢ (((𝑦 ∖ 𝐴) ∈ V ∧ (𝑦 ∖ 𝐴) ≠ ∅) → ∃𝑥 ∈ (𝑦 ∖ 𝐴)(𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅)
26	24, 25	mpan 702	. . . . . . . . 9 ⊢ ((𝑦 ∖ 𝐴) ≠ ∅ → ∃𝑥 ∈ (𝑦 ∖ 𝐴)(𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅)
27	26	necon1bi 2986	. . . . . . . 8 ⊢ (¬ ∃𝑥 ∈ (𝑦 ∖ 𝐴)(𝑥 ∩ (𝑦 ∖ 𝐴)) = ∅ → (𝑦 ∖ 𝐴) = ∅)
28	22, 27	syl 18	. . . . . . 7 ⊢ ((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) → (𝑦 ∖ 𝐴) = ∅)
29		ssdif0 4321	. . . . . . 7 ⊢ (𝑦 ⊆ 𝐴 ↔ (𝑦 ∖ 𝐴) = ∅)
30	28, 29	sylibr 237	. . . . . 6 ⊢ ((Tr 𝑦 ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) → 𝑦 ⊆ 𝐴)
31	30	adantlr 727	. . . . 5 ⊢ (((Tr 𝑦 ∧ 𝐵 ∈ 𝑦) ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) → 𝑦 ⊆ 𝐴)
32		simplr 780	. . . . 5 ⊢ (((Tr 𝑦 ∧ 𝐵 ∈ 𝑦) ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) → 𝐵 ∈ 𝑦)
33	31, 32	sseldd 3938	. . . 4 ⊢ (((Tr 𝑦 ∧ 𝐵 ∈ 𝑦) ∧ ∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴)) → 𝐵 ∈ 𝐴)
34	33	ex 417	. . 3 ⊢ ((Tr 𝑦 ∧ 𝐵 ∈ 𝑦) → (∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴) → 𝐵 ∈ 𝐴))
35	34	exlimiv 1960	. 2 ⊢ (∃𝑦(Tr 𝑦 ∧ 𝐵 ∈ 𝑦) → (∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴) → 𝐵 ∈ 𝐴))
36	35	com12 33	1 ⊢ (∀𝑥(𝑥 ⊆ 𝐴 → 𝑥 ∈ 𝐴) → (∃𝑦(Tr 𝑦 ∧ 𝐵 ∈ 𝑦) → 𝐵 ∈ 𝐴))

This proof depends on syntax axioms:  ¬ wn 3   → wi 4   ∧ wa 400  ∀wal 1568   = wceq 1570  ∃wex 1809   ∈ wcel 2143   ≠ wne 2958  ∀wral 3079  ∃wrex 3089  Vcvv 3455   ∖ cdif 3902   ∩ cin 3904   ⊆ wss 3905  ∅c0 4286  Tr wtr 5218

This proof depends on 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-10 2176  ax-12 2213  ax-ext 2735  ax-sep 5257  ax-reg 9550

This proof depends on definitions:  df-bi 210  df-an 401  df-or 861  df-3an 1105  df-tru 1573  df-fal 1583  df-ex 1810  df-nf 1814  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-in 3912  df-ss 3922  df-nul 4287  df-uni 4873  df-tr 5219

This theorem is used by:  setindtrs  43780