Theorem ssfirab 7123

Description: A subset of a finite set is finite if it is defined by a decidable property. (Contributed by Jim Kingdon, 27-May-2022.)

Hypotheses

Ref	Expression
ssfirab.a	⊢ (𝜑 → 𝐴 ∈ Fin)
ssfirab.dc	⊢ (𝜑 → ∀𝑥 ∈ 𝐴 DECID 𝜓)

Assertion

Ref	Expression
ssfirab	⊢ (𝜑 → {𝑥 ∈ 𝐴 ∣ 𝜓} ∈ Fin)

Distinct variable group:   𝑥,𝐴

Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑥)

Proof of Theorem ssfirab

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

Step	Hyp	Ref	Expression
1		rabeq 2792	. . 3 ⊢ (𝑤 = ∅ → {𝑥 ∈ 𝑤 ∣ 𝜓} = {𝑥 ∈ ∅ ∣ 𝜓})
2	1	eleq1d 2298	. 2 ⊢ (𝑤 = ∅ → ({𝑥 ∈ 𝑤 ∣ 𝜓} ∈ Fin ↔ {𝑥 ∈ ∅ ∣ 𝜓} ∈ Fin))
3		rabeq 2792	. . 3 ⊢ (𝑤 = 𝑦 → {𝑥 ∈ 𝑤 ∣ 𝜓} = {𝑥 ∈ 𝑦 ∣ 𝜓})
4	3	eleq1d 2298	. 2 ⊢ (𝑤 = 𝑦 → ({𝑥 ∈ 𝑤 ∣ 𝜓} ∈ Fin ↔ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin))
5		rabeq 2792	. . 3 ⊢ (𝑤 = (𝑦 ∪ {𝑧}) → {𝑥 ∈ 𝑤 ∣ 𝜓} = {𝑥 ∈ (𝑦 ∪ {𝑧}) ∣ 𝜓})
6	5	eleq1d 2298	. 2 ⊢ (𝑤 = (𝑦 ∪ {𝑧}) → ({𝑥 ∈ 𝑤 ∣ 𝜓} ∈ Fin ↔ {𝑥 ∈ (𝑦 ∪ {𝑧}) ∣ 𝜓} ∈ Fin))
7		rabeq 2792	. . 3 ⊢ (𝑤 = 𝐴 → {𝑥 ∈ 𝑤 ∣ 𝜓} = {𝑥 ∈ 𝐴 ∣ 𝜓})
8	7	eleq1d 2298	. 2 ⊢ (𝑤 = 𝐴 → ({𝑥 ∈ 𝑤 ∣ 𝜓} ∈ Fin ↔ {𝑥 ∈ 𝐴 ∣ 𝜓} ∈ Fin))
9		rab0 3521	. . . 4 ⊢ {𝑥 ∈ ∅ ∣ 𝜓} = ∅
10		0fi 7068	. . . 4 ⊢ ∅ ∈ Fin
11	9, 10	eqeltri 2302	. . 3 ⊢ {𝑥 ∈ ∅ ∣ 𝜓} ∈ Fin
12	11	a1i 9	. 2 ⊢ (𝜑 → {𝑥 ∈ ∅ ∣ 𝜓} ∈ Fin)
13		rabun2 3484	. . . . 5 ⊢ {𝑥 ∈ (𝑦 ∪ {𝑧}) ∣ 𝜓} = ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ {𝑥 ∈ {𝑧} ∣ 𝜓})
14		sbsbc 3033	. . . . . . . . . 10 ⊢ ([𝑧 / 𝑥]𝜓 ↔ [𝑧 / 𝑥]𝜓)
15		vex 2803	. . . . . . . . . . 11 ⊢ 𝑧 ∈ V
16		ralsns 3705	. . . . . . . . . . 11 ⊢ (𝑧 ∈ V → (∀𝑥 ∈ {𝑧}𝜓 ↔ [𝑧 / 𝑥]𝜓))
17	15, 16	ax-mp 5	. . . . . . . . . 10 ⊢ (∀𝑥 ∈ {𝑧}𝜓 ↔ [𝑧 / 𝑥]𝜓)
18	14, 17	bitr4i 187	. . . . . . . . 9 ⊢ ([𝑧 / 𝑥]𝜓 ↔ ∀𝑥 ∈ {𝑧}𝜓)
19		rabid2 2708	. . . . . . . . 9 ⊢ ({𝑧} = {𝑥 ∈ {𝑧} ∣ 𝜓} ↔ ∀𝑥 ∈ {𝑧}𝜓)
20	18, 19	sylbb2 138	. . . . . . . 8 ⊢ ([𝑧 / 𝑥]𝜓 → {𝑧} = {𝑥 ∈ {𝑧} ∣ 𝜓})
21	20	adantl 277	. . . . . . 7 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → {𝑧} = {𝑥 ∈ {𝑧} ∣ 𝜓})
22	21	uneq2d 3359	. . . . . 6 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ {𝑧}) = ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ {𝑥 ∈ {𝑧} ∣ 𝜓}))
23		simplr 528	. . . . . . 7 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin)
24	15	a1i 9	. . . . . . 7 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → 𝑧 ∈ V)
25		simprr 531	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) → 𝑧 ∈ (𝐴 ∖ 𝑦))
26	25	ad2antrr 488	. . . . . . . . 9 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → 𝑧 ∈ (𝐴 ∖ 𝑦))
27	26	eldifbd 3210	. . . . . . . 8 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → ¬ 𝑧 ∈ 𝑦)
28		elrabi 2957	. . . . . . . 8 ⊢ (𝑧 ∈ {𝑥 ∈ 𝑦 ∣ 𝜓} → 𝑧 ∈ 𝑦)
29	27, 28	nsyl 631	. . . . . . 7 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → ¬ 𝑧 ∈ {𝑥 ∈ 𝑦 ∣ 𝜓})
30		unsnfi 7106	. . . . . . 7 ⊢ (({𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin ∧ 𝑧 ∈ V ∧ ¬ 𝑧 ∈ {𝑥 ∈ 𝑦 ∣ 𝜓}) → ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ {𝑧}) ∈ Fin)
31	23, 24, 29, 30	syl3anc 1271	. . . . . 6 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ {𝑧}) ∈ Fin)
32	22, 31	eqeltrrd 2307	. . . . 5 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ {𝑥 ∈ {𝑧} ∣ 𝜓}) ∈ Fin)
33	13, 32	eqeltrid 2316	. . . 4 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ [𝑧 / 𝑥]𝜓) → {𝑥 ∈ (𝑦 ∪ {𝑧}) ∣ 𝜓} ∈ Fin)
34		ralsns 3705	. . . . . . . . . . . 12 ⊢ (𝑧 ∈ V → (∀𝑥 ∈ {𝑧} ¬ 𝜓 ↔ [𝑧 / 𝑥] ¬ 𝜓))
35	15, 34	ax-mp 5	. . . . . . . . . . 11 ⊢ (∀𝑥 ∈ {𝑧} ¬ 𝜓 ↔ [𝑧 / 𝑥] ¬ 𝜓)
36		sbsbc 3033	. . . . . . . . . . 11 ⊢ ([𝑧 / 𝑥] ¬ 𝜓 ↔ [𝑧 / 𝑥] ¬ 𝜓)
37		sbn 2003	. . . . . . . . . . 11 ⊢ ([𝑧 / 𝑥] ¬ 𝜓 ↔ ¬ [𝑧 / 𝑥]𝜓)
38	35, 36, 37	3bitr2ri 209	. . . . . . . . . 10 ⊢ (¬ [𝑧 / 𝑥]𝜓 ↔ ∀𝑥 ∈ {𝑧} ¬ 𝜓)
39		rabeq0 3522	. . . . . . . . . 10 ⊢ ({𝑥 ∈ {𝑧} ∣ 𝜓} = ∅ ↔ ∀𝑥 ∈ {𝑧} ¬ 𝜓)
40	38, 39	sylbb2 138	. . . . . . . . 9 ⊢ (¬ [𝑧 / 𝑥]𝜓 → {𝑥 ∈ {𝑧} ∣ 𝜓} = ∅)
41	40	adantl 277	. . . . . . . 8 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ ¬ [𝑧 / 𝑥]𝜓) → {𝑥 ∈ {𝑧} ∣ 𝜓} = ∅)
42	41	uneq2d 3359	. . . . . . 7 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ ¬ [𝑧 / 𝑥]𝜓) → ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ {𝑥 ∈ {𝑧} ∣ 𝜓}) = ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ ∅))
43		un0 3526	. . . . . . 7 ⊢ ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ ∅) = {𝑥 ∈ 𝑦 ∣ 𝜓}
44	42, 43	eqtrdi 2278	. . . . . 6 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ ¬ [𝑧 / 𝑥]𝜓) → ({𝑥 ∈ 𝑦 ∣ 𝜓} ∪ {𝑥 ∈ {𝑧} ∣ 𝜓}) = {𝑥 ∈ 𝑦 ∣ 𝜓})
45	13, 44	eqtrid 2274	. . . . 5 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ ¬ [𝑧 / 𝑥]𝜓) → {𝑥 ∈ (𝑦 ∪ {𝑧}) ∣ 𝜓} = {𝑥 ∈ 𝑦 ∣ 𝜓})
46		simplr 528	. . . . 5 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ ¬ [𝑧 / 𝑥]𝜓) → {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin)
47	45, 46	eqeltrd 2306	. . . 4 ⊢ (((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) ∧ ¬ [𝑧 / 𝑥]𝜓) → {𝑥 ∈ (𝑦 ∪ {𝑧}) ∣ 𝜓} ∈ Fin)
48		simplrr 536	. . . . . . 7 ⊢ ((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) → 𝑧 ∈ (𝐴 ∖ 𝑦))
49	48	eldifad 3209	. . . . . 6 ⊢ ((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) → 𝑧 ∈ 𝐴)
50		ssfirab.dc	. . . . . . 7 ⊢ (𝜑 → ∀𝑥 ∈ 𝐴 DECID 𝜓)
51	50	ad3antrrr 492	. . . . . 6 ⊢ ((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) → ∀𝑥 ∈ 𝐴 DECID 𝜓)
52		nfs1v 1990	. . . . . . . 8 ⊢ Ⅎ𝑥[𝑧 / 𝑥]𝜓
53	52	nfdc 1705	. . . . . . 7 ⊢ Ⅎ𝑥DECID [𝑧 / 𝑥]𝜓
54		sbequ12 1817	. . . . . . . 8 ⊢ (𝑥 = 𝑧 → (𝜓 ↔ [𝑧 / 𝑥]𝜓))
55	54	dcbid 843	. . . . . . 7 ⊢ (𝑥 = 𝑧 → (DECID 𝜓 ↔ DECID [𝑧 / 𝑥]𝜓))
56	53, 55	rspc 2902	. . . . . 6 ⊢ (𝑧 ∈ 𝐴 → (∀𝑥 ∈ 𝐴 DECID 𝜓 → DECID [𝑧 / 𝑥]𝜓))
57	49, 51, 56	sylc 62	. . . . 5 ⊢ ((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) → DECID [𝑧 / 𝑥]𝜓)
58		exmiddc 841	. . . . 5 ⊢ (DECID [𝑧 / 𝑥]𝜓 → ([𝑧 / 𝑥]𝜓 ∨ ¬ [𝑧 / 𝑥]𝜓))
59	57, 58	syl 14	. . . 4 ⊢ ((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) → ([𝑧 / 𝑥]𝜓 ∨ ¬ [𝑧 / 𝑥]𝜓))
60	33, 47, 59	mpjaodan 803	. . 3 ⊢ ((((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) ∧ {𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin) → {𝑥 ∈ (𝑦 ∪ {𝑧}) ∣ 𝜓} ∈ Fin)
61	60	ex 115	. 2 ⊢ (((𝜑 ∧ 𝑦 ∈ Fin) ∧ (𝑦 ⊆ 𝐴 ∧ 𝑧 ∈ (𝐴 ∖ 𝑦))) → ({𝑥 ∈ 𝑦 ∣ 𝜓} ∈ Fin → {𝑥 ∈ (𝑦 ∪ {𝑧}) ∣ 𝜓} ∈ Fin))
62		ssfirab.a	. 2 ⊢ (𝜑 → 𝐴 ∈ Fin)
63	2, 4, 6, 8, 12, 61, 62	findcard2sd 7076	1 ⊢ (𝜑 → {𝑥 ∈ 𝐴 ∣ 𝜓} ∈ Fin)

Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 104   ↔ wb 105   ∨ wo 713  DECID wdc 839   = wceq 1395  [wsb 1808   ∈ wcel 2200  ∀wral 2508  {crab 2512  Vcvv 2800  [wsbc 3029   ∖ cdif 3195   ∪ cun 3196   ⊆ wss 3198  ∅c0 3492  {csn 3667  Fincfn 6904

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 617  ax-in2 618  ax-io 714  ax-5 1493  ax-7 1494  ax-gen 1495  ax-ie1 1539  ax-ie2 1540  ax-8 1550  ax-10 1551  ax-11 1552  ax-i12 1553  ax-bndl 1555  ax-4 1556  ax-17 1572  ax-i9 1576  ax-ial 1580  ax-i5r 1581  ax-13 2202  ax-14 2203  ax-ext 2211  ax-coll 4202  ax-sep 4205  ax-nul 4213  ax-pow 4262  ax-pr 4297  ax-un 4528  ax-setind 4633  ax-iinf 4684

This theorem depends on definitions:  df-bi 117  df-dc 840  df-3or 1003  df-3an 1004  df-tru 1398  df-fal 1401  df-nf 1507  df-sb 1809  df-eu 2080  df-mo 2081  df-clab 2216  df-cleq 2222  df-clel 2225  df-nfc 2361  df-ne 2401  df-ral 2513  df-rex 2514  df-reu 2515  df-rab 2517  df-v 2802  df-sbc 3030  df-csb 3126  df-dif 3200  df-un 3202  df-in 3204  df-ss 3211  df-nul 3493  df-if 3604  df-pw 3652  df-sn 3673  df-pr 3674  df-op 3676  df-uni 3892  df-int 3927  df-iun 3970  df-br 4087  df-opab 4149  df-mpt 4150  df-tr 4186  df-id 4388  df-iord 4461  df-on 4463  df-suc 4466  df-iom 4687  df-xp 4729  df-rel 4730  df-cnv 4731  df-co 4732  df-dm 4733  df-rn 4734  df-res 4735  df-ima 4736  df-iota 5284  df-fun 5326  df-fn 5327  df-f 5328  df-f1 5329  df-fo 5330  df-f1o 5331  df-fv 5332  df-1o 6577  df-er 6697  df-en 6905  df-fin 6907

This theorem is referenced by:  ssfidc  7124  phivalfi  12777  hashdvds  12786  phiprmpw  12787  phimullem  12790  hashgcdeq  12805  lgsquadlemofi  15798  lgsquadlem1  15799  lgsquadlem2  15800  vtxedgfi  16100  vtxlpfi  16101