Theorem indexa 35818

Description: If for every element of an indexing set 𝐴 there exists a corresponding element of another set 𝐵, then there exists a subset of 𝐵 consisting only of those elements which are indexed by 𝐴. Used to avoid the Axiom of Choice in situations where only the range of the choice function is needed. (Contributed by Jeff Madsen, 2-Sep-2009.)

Assertion

Ref	Expression
indexa	⊢ ((𝐵 ∈ 𝑀 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑) → ∃𝑐(𝑐 ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝑐 𝜑 ∧ ∀𝑦 ∈ 𝑐 ∃𝑥 ∈ 𝐴 𝜑))

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

Allowed substitution hints:   𝜑(𝑥,𝑦)   𝑀(𝑥,𝑦,𝑐)

Proof of Theorem indexa

Dummy variables 𝑧 𝑤 𝑣 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		rabexg 5250	. 2 ⊢ (𝐵 ∈ 𝑀 → {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ∈ V)
2		ssrab2 4009	. . . 4 ⊢ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ⊆ 𝐵
3	2	a1i 11	. . 3 ⊢ (∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑 → {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ⊆ 𝐵)
4		nfv 1918	. . . . 5 ⊢ Ⅎ𝑦 𝑥 ∈ 𝐴
5		nfre1 3234	. . . . 5 ⊢ Ⅎ𝑦∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑
6		sbceq2a 3723	. . . . . . . . . . . . . 14 ⊢ (𝑤 = 𝑥 → ([𝑤 / 𝑥]𝜑 ↔ 𝜑))
7	6	rspcev 3552	. . . . . . . . . . . . 13 ⊢ ((𝑥 ∈ 𝐴 ∧ 𝜑) → ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥]𝜑)
8	7	ancoms 458	. . . . . . . . . . . 12 ⊢ ((𝜑 ∧ 𝑥 ∈ 𝐴) → ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥]𝜑)
9	8	anim1ci 615	. . . . . . . . . . 11 ⊢ (((𝜑 ∧ 𝑥 ∈ 𝐴) ∧ 𝑦 ∈ 𝐵) → (𝑦 ∈ 𝐵 ∧ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥]𝜑))
10	9	anasss 466	. . . . . . . . . 10 ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)) → (𝑦 ∈ 𝐵 ∧ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥]𝜑))
11	10	ancoms 458	. . . . . . . . 9 ⊢ (((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝜑) → (𝑦 ∈ 𝐵 ∧ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥]𝜑))
12		sbceq2a 3723	. . . . . . . . . . . 12 ⊢ (𝑧 = 𝑦 → ([𝑧 / 𝑦]𝜑 ↔ 𝜑))
13	12	sbcbidv 3770	. . . . . . . . . . 11 ⊢ (𝑧 = 𝑦 → ([𝑤 / 𝑥][𝑧 / 𝑦]𝜑 ↔ [𝑤 / 𝑥]𝜑))
14	13	rexbidv 3225	. . . . . . . . . 10 ⊢ (𝑧 = 𝑦 → (∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑 ↔ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥]𝜑))
15	14	elrab 3617	. . . . . . . . 9 ⊢ (𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ↔ (𝑦 ∈ 𝐵 ∧ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥]𝜑))
16	11, 15	sylibr 233	. . . . . . . 8 ⊢ (((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝜑) → 𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑})
17		sbceq2a 3723	. . . . . . . . 9 ⊢ (𝑣 = 𝑦 → ([𝑣 / 𝑦]𝜑 ↔ 𝜑))
18	17	rspcev 3552	. . . . . . . 8 ⊢ ((𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ∧ 𝜑) → ∃𝑣 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}[𝑣 / 𝑦]𝜑)
19	16, 18	sylancom 587	. . . . . . 7 ⊢ (((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝜑) → ∃𝑣 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}[𝑣 / 𝑦]𝜑)
20		nfcv 2906	. . . . . . . 8 ⊢ Ⅎ𝑣{𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}
21		nfcv 2906	. . . . . . . . . 10 ⊢ Ⅎ𝑦𝐴
22		nfcv 2906	. . . . . . . . . . 11 ⊢ Ⅎ𝑦𝑤
23		nfsbc1v 3731	. . . . . . . . . . 11 ⊢ Ⅎ𝑦[𝑧 / 𝑦]𝜑
24	22, 23	nfsbcw 3733	. . . . . . . . . 10 ⊢ Ⅎ𝑦[𝑤 / 𝑥][𝑧 / 𝑦]𝜑
25	21, 24	nfrex 3237	. . . . . . . . 9 ⊢ Ⅎ𝑦∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑
26		nfcv 2906	. . . . . . . . 9 ⊢ Ⅎ𝑦𝐵
27	25, 26	nfrabw 3311	. . . . . . . 8 ⊢ Ⅎ𝑦{𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}
28		nfsbc1v 3731	. . . . . . . 8 ⊢ Ⅎ𝑦[𝑣 / 𝑦]𝜑
29		nfv 1918	. . . . . . . 8 ⊢ Ⅎ𝑣𝜑
30	20, 27, 28, 29, 17	cbvrexfw 3360	. . . . . . 7 ⊢ (∃𝑣 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}[𝑣 / 𝑦]𝜑 ↔ ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑)
31	19, 30	sylib 217	. . . . . 6 ⊢ (((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝜑) → ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑)
32	31	exp31 419	. . . . 5 ⊢ (𝑥 ∈ 𝐴 → (𝑦 ∈ 𝐵 → (𝜑 → ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑)))
33	4, 5, 32	rexlimd 3245	. . . 4 ⊢ (𝑥 ∈ 𝐴 → (∃𝑦 ∈ 𝐵 𝜑 → ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑))
34	33	ralimia 3084	. . 3 ⊢ (∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑 → ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑)
35		nfsbc1v 3731	. . . . . . . . 9 ⊢ Ⅎ𝑥[𝑤 / 𝑥]𝜑
36		nfv 1918	. . . . . . . . 9 ⊢ Ⅎ𝑤𝜑
37	35, 36, 6	cbvrexw 3364	. . . . . . . 8 ⊢ (∃𝑤 ∈ 𝐴 [𝑤 / 𝑥]𝜑 ↔ ∃𝑥 ∈ 𝐴 𝜑)
38	14, 37	bitrdi 286	. . . . . . 7 ⊢ (𝑧 = 𝑦 → (∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑 ↔ ∃𝑥 ∈ 𝐴 𝜑))
39	38	elrab 3617	. . . . . 6 ⊢ (𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ↔ (𝑦 ∈ 𝐵 ∧ ∃𝑥 ∈ 𝐴 𝜑))
40	39	simprbi 496	. . . . 5 ⊢ (𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} → ∃𝑥 ∈ 𝐴 𝜑)
41	40	rgen 3073	. . . 4 ⊢ ∀𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}∃𝑥 ∈ 𝐴 𝜑
42	41	a1i 11	. . 3 ⊢ (∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑 → ∀𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}∃𝑥 ∈ 𝐴 𝜑)
43	3, 34, 42	3jca 1126	. 2 ⊢ (∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑 → ({𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑 ∧ ∀𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}∃𝑥 ∈ 𝐴 𝜑))
44		sseq1 3942	. . . . 5 ⊢ (𝑐 = {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} → (𝑐 ⊆ 𝐵 ↔ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ⊆ 𝐵))
45		nfcv 2906	. . . . . . . . 9 ⊢ Ⅎ𝑥𝐴
46		nfsbc1v 3731	. . . . . . . . 9 ⊢ Ⅎ𝑥[𝑤 / 𝑥][𝑧 / 𝑦]𝜑
47	45, 46	nfrex 3237	. . . . . . . 8 ⊢ Ⅎ𝑥∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑
48		nfcv 2906	. . . . . . . 8 ⊢ Ⅎ𝑥𝐵
49	47, 48	nfrabw 3311	. . . . . . 7 ⊢ Ⅎ𝑥{𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}
50	49	nfeq2 2923	. . . . . 6 ⊢ Ⅎ𝑥 𝑐 = {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}
51		nfcv 2906	. . . . . . 7 ⊢ Ⅎ𝑦𝑐
52	51, 27	rexeqf 3324	. . . . . 6 ⊢ (𝑐 = {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} → (∃𝑦 ∈ 𝑐 𝜑 ↔ ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑))
53	50, 52	ralbid 3158	. . . . 5 ⊢ (𝑐 = {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} → (∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝑐 𝜑 ↔ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑))
54	51, 27	raleqf 3323	. . . . 5 ⊢ (𝑐 = {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} → (∀𝑦 ∈ 𝑐 ∃𝑥 ∈ 𝐴 𝜑 ↔ ∀𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}∃𝑥 ∈ 𝐴 𝜑))
55	44, 53, 54	3anbi123d 1434	. . . 4 ⊢ (𝑐 = {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} → ((𝑐 ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝑐 𝜑 ∧ ∀𝑦 ∈ 𝑐 ∃𝑥 ∈ 𝐴 𝜑) ↔ ({𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑 ∧ ∀𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}∃𝑥 ∈ 𝐴 𝜑)))
56	55	spcegv 3526	. . 3 ⊢ ({𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ∈ V → (({𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑 ∧ ∀𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}∃𝑥 ∈ 𝐴 𝜑) → ∃𝑐(𝑐 ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝑐 𝜑 ∧ ∀𝑦 ∈ 𝑐 ∃𝑥 ∈ 𝐴 𝜑)))
57	56	imp 406	. 2 ⊢ (({𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ∈ V ∧ ({𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑} ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}𝜑 ∧ ∀𝑦 ∈ {𝑧 ∈ 𝐵 ∣ ∃𝑤 ∈ 𝐴 [𝑤 / 𝑥][𝑧 / 𝑦]𝜑}∃𝑥 ∈ 𝐴 𝜑)) → ∃𝑐(𝑐 ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝑐 𝜑 ∧ ∀𝑦 ∈ 𝑐 ∃𝑥 ∈ 𝐴 𝜑))
58	1, 43, 57	syl2an 595	1 ⊢ ((𝐵 ∈ 𝑀 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑) → ∃𝑐(𝑐 ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝑐 𝜑 ∧ ∀𝑦 ∈ 𝑐 ∃𝑥 ∈ 𝐴 𝜑))

Syntax hints:   → wi 4   ∧ wa 395   ∧ w3a 1085   = wceq 1539  ∃wex 1783   ∈ wcel 2108  ∀wral 3063  ∃wrex 3064  {crab 3067  Vcvv 3422  [wsbc 3711   ⊆ wss 3883

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1799  ax-4 1813  ax-5 1914  ax-6 1972  ax-7 2012  ax-8 2110  ax-9 2118  ax-10 2139  ax-11 2156  ax-12 2173  ax-ext 2709  ax-sep 5218

This theorem depends on definitions:  df-bi 206  df-an 396  df-or 844  df-3an 1087  df-tru 1542  df-ex 1784  df-nf 1788  df-sb 2069  df-clab 2716  df-cleq 2730  df-clel 2817  df-nfc 2888  df-ral 3068  df-rex 3069  df-rab 3072  df-v 3424  df-sbc 3712  df-in 3890  df-ss 3900

This theorem is referenced by: (None)