smfinfdmmbllem - Mathbox for Glauco Siliprandi

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Theorem smfinfdmmbllem 47088

Description: If a countable set of sigma-measurable functions have domains in the sigma-algebra, then their infimum function has the domain in the sigma-algebra. This is the fifth statement of Proposition 121H of [Fremlin1] p. 39 . (Contributed by Glauco Siliprandi, 1-Feb-2025.)

**Hypotheses**
Ref	Expression
smfinfdmmbllem.1	⊢ Ⅎ𝑛𝜑
smfinfdmmbllem.2	⊢ Ⅎ𝑥𝜑
smfinfdmmbllem.3	⊢ Ⅎ𝑚𝜑
smfinfdmmbllem.4	⊢ Ⅎ𝑥𝐹
smfinfdmmbllem.5	⊢ (𝜑 → 𝑀 ∈ ℤ)
smfinfdmmbllem.6	⊢ 𝑍 = (ℤ_≥‘𝑀)
smfinfdmmbllem.7	⊢ (𝜑 → 𝑆 ∈ SAlg)
smfinfdmmbllem.8	⊢ (𝜑 → 𝐹:𝑍⟶(SMblFn‘𝑆))
smfinfdmmbllem.9	⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → dom (𝐹‘𝑛) ∈ 𝑆)
smfinfdmmbllem.10	⊢ 𝐷 = {𝑥 ∈ ∩ 𝑛 ∈ 𝑍 dom (𝐹‘𝑛) ∣ ∃𝑦 ∈ ℝ ∀𝑛 ∈ 𝑍 𝑦 ≤ ((𝐹‘𝑛)‘𝑥)}
smfinfdmmbllem.11	⊢ 𝐺 = (𝑥 ∈ 𝐷 ↦ inf(ran (𝑛 ∈ 𝑍 ↦ ((𝐹‘𝑛)‘𝑥)), ℝ, < ))
smfinfdmmbllem.12	⊢ 𝐻 = (𝑛 ∈ 𝑍 ↦ (𝑚 ∈ ℕ ↦ {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)}))

**Assertion**
Ref	Expression
smfinfdmmbllem	⊢ (𝜑 → dom 𝐺 ∈ 𝑆)

Distinct variable groups: 𝐷,𝑚 𝑚,𝐹,𝑦 𝑦,𝐻 𝑆,𝑚,𝑛 𝑚,𝑍,𝑥,𝑛,𝑦 𝜑,𝑦 Allowed substitution hints: 𝜑(𝑥,𝑚,𝑛) 𝐷(𝑥,𝑦,𝑛) 𝑆(𝑥,𝑦) 𝐹(𝑥,𝑛) 𝐺(𝑥,𝑦,𝑚,𝑛) 𝐻(𝑥,𝑚,𝑛) 𝑀(𝑥,𝑦,𝑚,𝑛)

**Proof of Theorem smfinfdmmbllem**
Step	Hyp	Ref	Expression
1		smfinfdmmbllem.1	. . 3 ⊢ Ⅎ𝑛𝜑
2		smfinfdmmbllem.2	. . 3 ⊢ Ⅎ𝑥𝜑
3		smfinfdmmbllem.3	. . 3 ⊢ Ⅎ𝑚𝜑
4		smfinfdmmbllem.4	. . 3 ⊢ Ⅎ𝑥𝐹
5		smfinfdmmbllem.7	. . . . . 6 ⊢ (𝜑 → 𝑆 ∈ SAlg)
6	5	adantr 480	. . . . 5 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → 𝑆 ∈ SAlg)
7		smfinfdmmbllem.8	. . . . . 6 ⊢ (𝜑 → 𝐹:𝑍⟶(SMblFn‘𝑆))
8	7	ffvelcdmda 7029	. . . . 5 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → (𝐹‘𝑛) ∈ (SMblFn‘𝑆))
9		eqid 2736	. . . . 5 ⊢ dom (𝐹‘𝑛) = dom (𝐹‘𝑛)
10	6, 8, 9	smff 46972	. . . 4 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → (𝐹‘𝑛):dom (𝐹‘𝑛)⟶ℝ)
11	10	frexr 45625	. . 3 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → (𝐹‘𝑛):dom (𝐹‘𝑛)⟶ℝ^*)
12		smfinfdmmbllem.10	. . 3 ⊢ 𝐷 = {𝑥 ∈ ∩ 𝑛 ∈ 𝑍 dom (𝐹‘𝑛) ∣ ∃𝑦 ∈ ℝ ∀𝑛 ∈ 𝑍 𝑦 ≤ ((𝐹‘𝑛)‘𝑥)}
13		smfinfdmmbllem.11	. . 3 ⊢ 𝐺 = (𝑥 ∈ 𝐷 ↦ inf(ran (𝑛 ∈ 𝑍 ↦ ((𝐹‘𝑛)‘𝑥)), ℝ, < ))
14		smfinfdmmbllem.12	. . 3 ⊢ 𝐻 = (𝑛 ∈ 𝑍 ↦ (𝑚 ∈ ℕ ↦ {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)}))
15	1, 2, 3, 4, 11, 12, 13, 14	finfdm2 47087	. 2 ⊢ (𝜑 → dom 𝐺 = ∪ 𝑚 ∈ ℕ ∩ 𝑛 ∈ 𝑍 ((𝐻‘𝑛)‘𝑚))
16		nfcv 2898	. . 3 ⊢ Ⅎ𝑚𝑆
17		nfcv 2898	. . 3 ⊢ Ⅎ𝑚ℕ
18		nnct 13904	. . . 4 ⊢ ℕ ≼ ω
19	18	a1i 11	. . 3 ⊢ (𝜑 → ℕ ≼ ω)
20		nfv 1915	. . . . 5 ⊢ Ⅎ𝑛 𝑚 ∈ ℕ
21	1, 20	nfan 1900	. . . 4 ⊢ Ⅎ𝑛(𝜑 ∧ 𝑚 ∈ ℕ)
22		nfcv 2898	. . . 4 ⊢ Ⅎ𝑛𝑆
23		nfcv 2898	. . . 4 ⊢ Ⅎ𝑛𝑍
24	5	adantr 480	. . . 4 ⊢ ((𝜑 ∧ 𝑚 ∈ ℕ) → 𝑆 ∈ SAlg)
25		smfinfdmmbllem.6	. . . . . 6 ⊢ 𝑍 = (ℤ_≥‘𝑀)
26	25	uzct 45304	. . . . 5 ⊢ 𝑍 ≼ ω
27	26	a1i 11	. . . 4 ⊢ ((𝜑 ∧ 𝑚 ∈ ℕ) → 𝑍 ≼ ω)
28		smfinfdmmbllem.5	. . . . . 6 ⊢ (𝜑 → 𝑀 ∈ ℤ)
29	28, 25	uzn0d 45665	. . . . 5 ⊢ (𝜑 → 𝑍 ≠ ∅)
30	29	adantr 480	. . . 4 ⊢ ((𝜑 ∧ 𝑚 ∈ ℕ) → 𝑍 ≠ ∅)
31	24	adantr 480	. . . . . 6 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → 𝑆 ∈ SAlg)
32		smfinfdmmbllem.9	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → dom (𝐹‘𝑛) ∈ 𝑆)
33	32	adantlr 715	. . . . . 6 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → dom (𝐹‘𝑛) ∈ 𝑆)
34	31, 33	salrestss 46601	. . . . 5 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → (𝑆 ↾_t dom (𝐹‘𝑛)) ⊆ 𝑆)
35		nfv 1915	. . . . . . . . . 10 ⊢ Ⅎ𝑚 𝑛 ∈ 𝑍
36	3, 35	nfan 1900	. . . . . . . . 9 ⊢ Ⅎ𝑚(𝜑 ∧ 𝑛 ∈ 𝑍)
37		nfcv 2898	. . . . . . . . . . . 12 ⊢ Ⅎ𝑥𝑛
38	4, 37	nffv 6844	. . . . . . . . . . 11 ⊢ Ⅎ𝑥(𝐹‘𝑛)
39	8	adantlr 715	. . . . . . . . . . 11 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → (𝐹‘𝑛) ∈ (SMblFn‘𝑆))
40		nnre 12152	. . . . . . . . . . . . . 14 ⊢ (𝑚 ∈ ℕ → 𝑚 ∈ ℝ)
41	40	renegcld 11564	. . . . . . . . . . . . 13 ⊢ (𝑚 ∈ ℕ → -𝑚 ∈ ℝ)
42	41	rexrd 11182	. . . . . . . . . . . 12 ⊢ (𝑚 ∈ ℕ → -𝑚 ∈ ℝ^*)
43	42	ad2antlr 727	. . . . . . . . . . 11 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → -𝑚 ∈ ℝ^*)
44	38, 31, 39, 9, 43	smfpimgtxr 47020	. . . . . . . . . 10 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)} ∈ (𝑆 ↾_t dom (𝐹‘𝑛)))
45	44	an32s 652	. . . . . . . . 9 ⊢ (((𝜑 ∧ 𝑛 ∈ 𝑍) ∧ 𝑚 ∈ ℕ) → {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)} ∈ (𝑆 ↾_t dom (𝐹‘𝑛)))
46	36, 45	fmptd2f 45475	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → (𝑚 ∈ ℕ ↦ {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)}):ℕ⟶(𝑆 ↾_t dom (𝐹‘𝑛)))
47		simpr 484	. . . . . . . . . 10 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → 𝑛 ∈ 𝑍)
48		nnex 12151	. . . . . . . . . . 11 ⊢ ℕ ∈ V
49	48	mptex 7169	. . . . . . . . . 10 ⊢ (𝑚 ∈ ℕ ↦ {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)}) ∈ V
50	14	fvmpt2 6952	. . . . . . . . . 10 ⊢ ((𝑛 ∈ 𝑍 ∧ (𝑚 ∈ ℕ ↦ {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)}) ∈ V) → (𝐻‘𝑛) = (𝑚 ∈ ℕ ↦ {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)}))
51	47, 49, 50	sylancl 586	. . . . . . . . 9 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → (𝐻‘𝑛) = (𝑚 ∈ ℕ ↦ {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)}))
52	51	feq1d 6644	. . . . . . . 8 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → ((𝐻‘𝑛):ℕ⟶(𝑆 ↾_t dom (𝐹‘𝑛)) ↔ (𝑚 ∈ ℕ ↦ {𝑥 ∈ dom (𝐹‘𝑛) ∣ -𝑚 < ((𝐹‘𝑛)‘𝑥)}):ℕ⟶(𝑆 ↾_t dom (𝐹‘𝑛))))
53	46, 52	mpbird 257	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑍) → (𝐻‘𝑛):ℕ⟶(𝑆 ↾_t dom (𝐹‘𝑛)))
54	53	adantlr 715	. . . . . 6 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → (𝐻‘𝑛):ℕ⟶(𝑆 ↾_t dom (𝐹‘𝑛)))
55		simplr 768	. . . . . 6 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → 𝑚 ∈ ℕ)
56	54, 55	ffvelcdmd 7030	. . . . 5 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → ((𝐻‘𝑛)‘𝑚) ∈ (𝑆 ↾_t dom (𝐹‘𝑛)))
57	34, 56	sseldd 3934	. . . 4 ⊢ (((𝜑 ∧ 𝑚 ∈ ℕ) ∧ 𝑛 ∈ 𝑍) → ((𝐻‘𝑛)‘𝑚) ∈ 𝑆)
58	21, 22, 23, 24, 27, 30, 57	saliinclf 46566	. . 3 ⊢ ((𝜑 ∧ 𝑚 ∈ ℕ) → ∩ 𝑛 ∈ 𝑍 ((𝐻‘𝑛)‘𝑚) ∈ 𝑆)
59	3, 16, 17, 5, 19, 58	saliunclf 46562	. 2 ⊢ (𝜑 → ∪ 𝑚 ∈ ℕ ∩ 𝑛 ∈ 𝑍 ((𝐻‘𝑛)‘𝑚) ∈ 𝑆)
60	15, 59	eqeltrd 2836	1 ⊢ (𝜑 → dom 𝐺 ∈ 𝑆)

Colors of variables: wff setvar class

Syntax hints: → wi 4 ∧ wa 395 = wceq 1541 Ⅎwnf 1784 ∈ wcel 2113 Ⅎwnfc 2883 ≠ wne 2932 ∀wral 3051 ∃wrex 3060 {crab 3399 Vcvv 3440 ∅c0 4285 ∪ ciun 4946 ∩ ciin 4947 class class class wbr 5098 ↦ cmpt 5179 dom cdm 5624 ran crn 5625 ⟶wf 6488 ‘cfv 6492 (class class class)co 7358 ωcom 7808 ≼ cdom 8881 infcinf 9344 ℝcr 11025 ℝ^*cxr 11165 < clt 11166 ≤ cle 11167 -cneg 11365 ℕcn 12145 ℤcz 12488 ℤ_≥cuz 12751 ↾_t crest 17340 SAlgcsalg 46548 SMblFncsmblfn 46935

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1968 ax-7 2009 ax-8 2115 ax-9 2123 ax-10 2146 ax-11 2162 ax-12 2184 ax-ext 2708 ax-rep 5224 ax-sep 5241 ax-nul 5251 ax-pow 5310 ax-pr 5377 ax-un 7680 ax-inf2 9550 ax-cc 10345 ax-ac2 10373 ax-cnex 11082 ax-resscn 11083 ax-1cn 11084 ax-icn 11085 ax-addcl 11086 ax-addrcl 11087 ax-mulcl 11088 ax-mulrcl 11089 ax-mulcom 11090 ax-addass 11091 ax-mulass 11092 ax-distr 11093 ax-i2m1 11094 ax-1ne0 11095 ax-1rid 11096 ax-rnegex 11097 ax-rrecex 11098 ax-cnre 11099 ax-pre-lttri 11100 ax-pre-lttrn 11101 ax-pre-ltadd 11102 ax-pre-mulgt0 11103 ax-pre-sup 11104

This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1544 df-fal 1554 df-ex 1781 df-nf 1785 df-sb 2068 df-mo 2539 df-eu 2569 df-clab 2715 df-cleq 2728 df-clel 2811 df-nfc 2885 df-ne 2933 df-nel 3037 df-ral 3052 df-rex 3061 df-rmo 3350 df-reu 3351 df-rab 3400 df-v 3442 df-sbc 3741 df-csb 3850 df-dif 3904 df-un 3906 df-in 3908 df-ss 3918 df-pss 3921 df-nul 4286 df-if 4480 df-pw 4556 df-sn 4581 df-pr 4583 df-op 4587 df-uni 4864 df-int 4903 df-iun 4948 df-iin 4949 df-br 5099 df-opab 5161 df-mpt 5180 df-tr 5206 df-id 5519 df-eprel 5524 df-po 5532 df-so 5533 df-fr 5577 df-se 5578 df-we 5579 df-xp 5630 df-rel 5631 df-cnv 5632 df-co 5633 df-dm 5634 df-rn 5635 df-res 5636 df-ima 5637 df-pred 6259 df-ord 6320 df-on 6321 df-lim 6322 df-suc 6323 df-iota 6448 df-fun 6494 df-fn 6495 df-f 6496 df-f1 6497 df-fo 6498 df-f1o 6499 df-fv 6500 df-isom 6501 df-riota 7315 df-ov 7361 df-oprab 7362 df-mpo 7363 df-om 7809 df-1st 7933 df-2nd 7934 df-frecs 8223 df-wrecs 8254 df-recs 8303 df-rdg 8341 df-1o 8397 df-2o 8398 df-oadd 8401 df-omul 8402 df-er 8635 df-map 8765 df-pm 8766 df-en 8884 df-dom 8885 df-sdom 8886 df-fin 8887 df-sup 9345 df-inf 9346 df-oi 9415 df-card 9851 df-acn 9854 df-ac 10026 df-pnf 11168 df-mnf 11169 df-xr 11170 df-ltxr 11171 df-le 11172 df-sub 11366 df-neg 11367 df-div 11795 df-nn 12146 df-n0 12402 df-z 12489 df-uz 12752 df-q 12862 df-rp 12906 df-ioo 13265 df-ico 13267 df-fl 13712 df-rest 17342 df-salg 46549 df-smblfn 46936

This theorem is referenced by: smfinfdmmbl 47089

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