Mathbox for Glauco Siliprandi |
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Mirrors > Home > MPE Home > Th. List > Mathboxes > fouriercn | Structured version Visualization version GIF version |
Description: If the derivative of 𝐹 is continuous, then the Fourier series for 𝐹 converges to 𝐹 everywhere and the hypothesis are simpler than those for the more general case of a piecewise smooth function (see fourierd 42514 for a comparison). (Contributed by Glauco Siliprandi, 11-Dec-2019.) |
Ref | Expression |
---|---|
fouriercn.f | ⊢ (𝜑 → 𝐹:ℝ⟶ℝ) |
fouriercn.t | ⊢ 𝑇 = (2 · π) |
fouriercn.per | ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → (𝐹‘(𝑥 + 𝑇)) = (𝐹‘𝑥)) |
fouriercn.dv | ⊢ (𝜑 → (ℝ D 𝐹) ∈ (ℝ–cn→ℂ)) |
fouriercn.g | ⊢ 𝐺 = ((ℝ D 𝐹) ↾ (-π(,)π)) |
fouriercn.x | ⊢ (𝜑 → 𝑋 ∈ ℝ) |
fouriercn.a | ⊢ 𝐴 = (𝑛 ∈ ℕ0 ↦ (∫(-π(,)π)((𝐹‘𝑥) · (cos‘(𝑛 · 𝑥))) d𝑥 / π)) |
fouriercn.b | ⊢ 𝐵 = (𝑛 ∈ ℕ ↦ (∫(-π(,)π)((𝐹‘𝑥) · (sin‘(𝑛 · 𝑥))) d𝑥 / π)) |
Ref | Expression |
---|---|
fouriercn | ⊢ (𝜑 → (((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = (𝐹‘𝑋)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fouriercn.f | . 2 ⊢ (𝜑 → 𝐹:ℝ⟶ℝ) | |
2 | fouriercn.t | . 2 ⊢ 𝑇 = (2 · π) | |
3 | fouriercn.per | . 2 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → (𝐹‘(𝑥 + 𝑇)) = (𝐹‘𝑥)) | |
4 | fouriercn.g | . 2 ⊢ 𝐺 = ((ℝ D 𝐹) ↾ (-π(,)π)) | |
5 | 4 | dmeqi 5776 | . . . . . 6 ⊢ dom 𝐺 = dom ((ℝ D 𝐹) ↾ (-π(,)π)) |
6 | ioossre 12801 | . . . . . . . 8 ⊢ (-π(,)π) ⊆ ℝ | |
7 | fouriercn.dv | . . . . . . . . 9 ⊢ (𝜑 → (ℝ D 𝐹) ∈ (ℝ–cn→ℂ)) | |
8 | cncff 23504 | . . . . . . . . 9 ⊢ ((ℝ D 𝐹) ∈ (ℝ–cn→ℂ) → (ℝ D 𝐹):ℝ⟶ℂ) | |
9 | fdm 6525 | . . . . . . . . 9 ⊢ ((ℝ D 𝐹):ℝ⟶ℂ → dom (ℝ D 𝐹) = ℝ) | |
10 | 7, 8, 9 | 3syl 18 | . . . . . . . 8 ⊢ (𝜑 → dom (ℝ D 𝐹) = ℝ) |
11 | 6, 10 | sseqtrrid 4023 | . . . . . . 7 ⊢ (𝜑 → (-π(,)π) ⊆ dom (ℝ D 𝐹)) |
12 | ssdmres 5879 | . . . . . . 7 ⊢ ((-π(,)π) ⊆ dom (ℝ D 𝐹) ↔ dom ((ℝ D 𝐹) ↾ (-π(,)π)) = (-π(,)π)) | |
13 | 11, 12 | sylib 220 | . . . . . 6 ⊢ (𝜑 → dom ((ℝ D 𝐹) ↾ (-π(,)π)) = (-π(,)π)) |
14 | 5, 13 | syl5eq 2871 | . . . . 5 ⊢ (𝜑 → dom 𝐺 = (-π(,)π)) |
15 | 14 | difeq2d 4102 | . . . 4 ⊢ (𝜑 → ((-π(,)π) ∖ dom 𝐺) = ((-π(,)π) ∖ (-π(,)π))) |
16 | difid 4333 | . . . 4 ⊢ ((-π(,)π) ∖ (-π(,)π)) = ∅ | |
17 | 15, 16 | syl6eq 2875 | . . 3 ⊢ (𝜑 → ((-π(,)π) ∖ dom 𝐺) = ∅) |
18 | 0fin 8749 | . . 3 ⊢ ∅ ∈ Fin | |
19 | 17, 18 | eqeltrdi 2924 | . 2 ⊢ (𝜑 → ((-π(,)π) ∖ dom 𝐺) ∈ Fin) |
20 | rescncf 23508 | . . . 4 ⊢ ((-π(,)π) ⊆ ℝ → ((ℝ D 𝐹) ∈ (ℝ–cn→ℂ) → ((ℝ D 𝐹) ↾ (-π(,)π)) ∈ ((-π(,)π)–cn→ℂ))) | |
21 | 6, 7, 20 | mpsyl 68 | . . 3 ⊢ (𝜑 → ((ℝ D 𝐹) ↾ (-π(,)π)) ∈ ((-π(,)π)–cn→ℂ)) |
22 | 4 | a1i 11 | . . 3 ⊢ (𝜑 → 𝐺 = ((ℝ D 𝐹) ↾ (-π(,)π))) |
23 | 14 | oveq1d 7174 | . . 3 ⊢ (𝜑 → (dom 𝐺–cn→ℂ) = ((-π(,)π)–cn→ℂ)) |
24 | 21, 22, 23 | 3eltr4d 2931 | . 2 ⊢ (𝜑 → 𝐺 ∈ (dom 𝐺–cn→ℂ)) |
25 | pire 25047 | . . . . . 6 ⊢ π ∈ ℝ | |
26 | 25 | renegcli 10950 | . . . . 5 ⊢ -π ∈ ℝ |
27 | 25 | rexri 10702 | . . . . 5 ⊢ π ∈ ℝ* |
28 | icossre 12820 | . . . . 5 ⊢ ((-π ∈ ℝ ∧ π ∈ ℝ*) → (-π[,)π) ⊆ ℝ) | |
29 | 26, 27, 28 | mp2an 690 | . . . 4 ⊢ (-π[,)π) ⊆ ℝ |
30 | eldifi 4106 | . . . 4 ⊢ (𝑥 ∈ ((-π[,)π) ∖ dom 𝐺) → 𝑥 ∈ (-π[,)π)) | |
31 | 29, 30 | sseldi 3968 | . . 3 ⊢ (𝑥 ∈ ((-π[,)π) ∖ dom 𝐺) → 𝑥 ∈ ℝ) |
32 | limcresi 24486 | . . . . . 6 ⊢ ((ℝ D 𝐹) limℂ 𝑥) ⊆ (((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (𝑥(,)+∞))) limℂ 𝑥) | |
33 | 4 | reseq1i 5852 | . . . . . . . 8 ⊢ (𝐺 ↾ (𝑥(,)+∞)) = (((ℝ D 𝐹) ↾ (-π(,)π)) ↾ (𝑥(,)+∞)) |
34 | resres 5869 | . . . . . . . 8 ⊢ (((ℝ D 𝐹) ↾ (-π(,)π)) ↾ (𝑥(,)+∞)) = ((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (𝑥(,)+∞))) | |
35 | 33, 34 | eqtr2i 2848 | . . . . . . 7 ⊢ ((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (𝑥(,)+∞))) = (𝐺 ↾ (𝑥(,)+∞)) |
36 | 35 | oveq1i 7169 | . . . . . 6 ⊢ (((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (𝑥(,)+∞))) limℂ 𝑥) = ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) |
37 | 32, 36 | sseqtri 4006 | . . . . 5 ⊢ ((ℝ D 𝐹) limℂ 𝑥) ⊆ ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) |
38 | 7 | adantr 483 | . . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → (ℝ D 𝐹) ∈ (ℝ–cn→ℂ)) |
39 | simpr 487 | . . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → 𝑥 ∈ ℝ) | |
40 | 38, 39 | cnlimci 24490 | . . . . 5 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((ℝ D 𝐹)‘𝑥) ∈ ((ℝ D 𝐹) limℂ 𝑥)) |
41 | 37, 40 | sseldi 3968 | . . . 4 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((ℝ D 𝐹)‘𝑥) ∈ ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥)) |
42 | 41 | ne0d 4304 | . . 3 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) ≠ ∅) |
43 | 31, 42 | sylan2 594 | . 2 ⊢ ((𝜑 ∧ 𝑥 ∈ ((-π[,)π) ∖ dom 𝐺)) → ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) ≠ ∅) |
44 | negpitopissre 25127 | . . . 4 ⊢ (-π(,]π) ⊆ ℝ | |
45 | eldifi 4106 | . . . 4 ⊢ (𝑥 ∈ ((-π(,]π) ∖ dom 𝐺) → 𝑥 ∈ (-π(,]π)) | |
46 | 44, 45 | sseldi 3968 | . . 3 ⊢ (𝑥 ∈ ((-π(,]π) ∖ dom 𝐺) → 𝑥 ∈ ℝ) |
47 | limcresi 24486 | . . . . . 6 ⊢ ((ℝ D 𝐹) limℂ 𝑥) ⊆ (((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (-∞(,)𝑥))) limℂ 𝑥) | |
48 | 4 | reseq1i 5852 | . . . . . . . 8 ⊢ (𝐺 ↾ (-∞(,)𝑥)) = (((ℝ D 𝐹) ↾ (-π(,)π)) ↾ (-∞(,)𝑥)) |
49 | resres 5869 | . . . . . . . 8 ⊢ (((ℝ D 𝐹) ↾ (-π(,)π)) ↾ (-∞(,)𝑥)) = ((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (-∞(,)𝑥))) | |
50 | 48, 49 | eqtr2i 2848 | . . . . . . 7 ⊢ ((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (-∞(,)𝑥))) = (𝐺 ↾ (-∞(,)𝑥)) |
51 | 50 | oveq1i 7169 | . . . . . 6 ⊢ (((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (-∞(,)𝑥))) limℂ 𝑥) = ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) |
52 | 47, 51 | sseqtri 4006 | . . . . 5 ⊢ ((ℝ D 𝐹) limℂ 𝑥) ⊆ ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) |
53 | 52, 40 | sseldi 3968 | . . . 4 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((ℝ D 𝐹)‘𝑥) ∈ ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥)) |
54 | 53 | ne0d 4304 | . . 3 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) ≠ ∅) |
55 | 46, 54 | sylan2 594 | . 2 ⊢ ((𝜑 ∧ 𝑥 ∈ ((-π(,]π) ∖ dom 𝐺)) → ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) ≠ ∅) |
56 | eqid 2824 | . 2 ⊢ (topGen‘ran (,)) = (topGen‘ran (,)) | |
57 | ax-resscn 10597 | . . . . . . 7 ⊢ ℝ ⊆ ℂ | |
58 | 57 | a1i 11 | . . . . . 6 ⊢ (𝜑 → ℝ ⊆ ℂ) |
59 | 1, 58 | fssd 6531 | . . . . . . 7 ⊢ (𝜑 → 𝐹:ℝ⟶ℂ) |
60 | ssid 3992 | . . . . . . . 8 ⊢ ℝ ⊆ ℝ | |
61 | 60 | a1i 11 | . . . . . . 7 ⊢ (𝜑 → ℝ ⊆ ℝ) |
62 | dvcn 24521 | . . . . . . 7 ⊢ (((ℝ ⊆ ℂ ∧ 𝐹:ℝ⟶ℂ ∧ ℝ ⊆ ℝ) ∧ dom (ℝ D 𝐹) = ℝ) → 𝐹 ∈ (ℝ–cn→ℂ)) | |
63 | 58, 59, 61, 10, 62 | syl31anc 1369 | . . . . . 6 ⊢ (𝜑 → 𝐹 ∈ (ℝ–cn→ℂ)) |
64 | cncffvrn 23509 | . . . . . 6 ⊢ ((ℝ ⊆ ℂ ∧ 𝐹 ∈ (ℝ–cn→ℂ)) → (𝐹 ∈ (ℝ–cn→ℝ) ↔ 𝐹:ℝ⟶ℝ)) | |
65 | 58, 63, 64 | syl2anc 586 | . . . . 5 ⊢ (𝜑 → (𝐹 ∈ (ℝ–cn→ℝ) ↔ 𝐹:ℝ⟶ℝ)) |
66 | 1, 65 | mpbird 259 | . . . 4 ⊢ (𝜑 → 𝐹 ∈ (ℝ–cn→ℝ)) |
67 | eqid 2824 | . . . . . 6 ⊢ (TopOpen‘ℂfld) = (TopOpen‘ℂfld) | |
68 | 67 | tgioo2 23414 | . . . . . 6 ⊢ (topGen‘ran (,)) = ((TopOpen‘ℂfld) ↾t ℝ) |
69 | 67, 68, 68 | cncfcn 23520 | . . . . 5 ⊢ ((ℝ ⊆ ℂ ∧ ℝ ⊆ ℂ) → (ℝ–cn→ℝ) = ((topGen‘ran (,)) Cn (topGen‘ran (,)))) |
70 | 58, 58, 69 | syl2anc 586 | . . . 4 ⊢ (𝜑 → (ℝ–cn→ℝ) = ((topGen‘ran (,)) Cn (topGen‘ran (,)))) |
71 | 66, 70 | eleqtrd 2918 | . . 3 ⊢ (𝜑 → 𝐹 ∈ ((topGen‘ran (,)) Cn (topGen‘ran (,)))) |
72 | fouriercn.x | . . 3 ⊢ (𝜑 → 𝑋 ∈ ℝ) | |
73 | uniretop 23374 | . . . 4 ⊢ ℝ = ∪ (topGen‘ran (,)) | |
74 | 73 | cncnpi 21889 | . . 3 ⊢ ((𝐹 ∈ ((topGen‘ran (,)) Cn (topGen‘ran (,))) ∧ 𝑋 ∈ ℝ) → 𝐹 ∈ (((topGen‘ran (,)) CnP (topGen‘ran (,)))‘𝑋)) |
75 | 71, 72, 74 | syl2anc 586 | . 2 ⊢ (𝜑 → 𝐹 ∈ (((topGen‘ran (,)) CnP (topGen‘ran (,)))‘𝑋)) |
76 | fouriercn.a | . 2 ⊢ 𝐴 = (𝑛 ∈ ℕ0 ↦ (∫(-π(,)π)((𝐹‘𝑥) · (cos‘(𝑛 · 𝑥))) d𝑥 / π)) | |
77 | fouriercn.b | . 2 ⊢ 𝐵 = (𝑛 ∈ ℕ ↦ (∫(-π(,)π)((𝐹‘𝑥) · (sin‘(𝑛 · 𝑥))) d𝑥 / π)) | |
78 | 1, 2, 3, 4, 19, 24, 43, 55, 56, 75, 76, 77 | fouriercnp 42518 | 1 ⊢ (𝜑 → (((𝐴‘0) / 2) + Σ𝑛 ∈ ℕ (((𝐴‘𝑛) · (cos‘(𝑛 · 𝑋))) + ((𝐵‘𝑛) · (sin‘(𝑛 · 𝑋))))) = (𝐹‘𝑋)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 = wceq 1536 ∈ wcel 2113 ≠ wne 3019 ∖ cdif 3936 ∩ cin 3938 ⊆ wss 3939 ∅c0 4294 ↦ cmpt 5149 dom cdm 5558 ran crn 5559 ↾ cres 5560 ⟶wf 6354 ‘cfv 6358 (class class class)co 7159 Fincfn 8512 ℂcc 10538 ℝcr 10539 0cc0 10540 + caddc 10543 · cmul 10545 +∞cpnf 10675 -∞cmnf 10676 ℝ*cxr 10677 -cneg 10874 / cdiv 11300 ℕcn 11641 2c2 11695 ℕ0cn0 11900 (,)cioo 12741 (,]cioc 12742 [,)cico 12743 Σcsu 15045 sincsin 15420 cosccos 15421 πcpi 15423 TopOpenctopn 16698 topGenctg 16714 ℂfldccnfld 20548 Cn ccn 21835 CnP ccnp 21836 –cn→ccncf 23487 ∫citg 24222 limℂ climc 24463 D cdv 24464 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1910 ax-6 1969 ax-7 2014 ax-8 2115 ax-9 2123 ax-10 2144 ax-11 2160 ax-12 2176 ax-ext 2796 ax-rep 5193 ax-sep 5206 ax-nul 5213 ax-pow 5269 ax-pr 5333 ax-un 7464 ax-inf2 9107 ax-cc 9860 ax-cnex 10596 ax-resscn 10597 ax-1cn 10598 ax-icn 10599 ax-addcl 10600 ax-addrcl 10601 ax-mulcl 10602 ax-mulrcl 10603 ax-mulcom 10604 ax-addass 10605 ax-mulass 10606 ax-distr 10607 ax-i2m1 10608 ax-1ne0 10609 ax-1rid 10610 ax-rnegex 10611 ax-rrecex 10612 ax-cnre 10613 ax-pre-lttri 10614 ax-pre-lttrn 10615 ax-pre-ltadd 10616 ax-pre-mulgt0 10617 ax-pre-sup 10618 ax-addf 10619 ax-mulf 10620 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1539 df-fal 1549 df-ex 1780 df-nf 1784 df-sb 2069 df-mo 2621 df-eu 2653 df-clab 2803 df-cleq 2817 df-clel 2896 df-nfc 2966 df-ne 3020 df-nel 3127 df-ral 3146 df-rex 3147 df-reu 3148 df-rmo 3149 df-rab 3150 df-v 3499 df-sbc 3776 df-csb 3887 df-dif 3942 df-un 3944 df-in 3946 df-ss 3955 df-pss 3957 df-symdif 4222 df-nul 4295 df-if 4471 df-pw 4544 df-sn 4571 df-pr 4573 df-tp 4575 df-op 4577 df-uni 4842 df-int 4880 df-iun 4924 df-iin 4925 df-disj 5035 df-br 5070 df-opab 5132 df-mpt 5150 df-tr 5176 df-id 5463 df-eprel 5468 df-po 5477 df-so 5478 df-fr 5517 df-se 5518 df-we 5519 df-xp 5564 df-rel 5565 df-cnv 5566 df-co 5567 df-dm 5568 df-rn 5569 df-res 5570 df-ima 5571 df-pred 6151 df-ord 6197 df-on 6198 df-lim 6199 df-suc 6200 df-iota 6317 df-fun 6360 df-fn 6361 df-f 6362 df-f1 6363 df-fo 6364 df-f1o 6365 df-fv 6366 df-isom 6367 df-riota 7117 df-ov 7162 df-oprab 7163 df-mpo 7164 df-of 7412 df-ofr 7413 df-om 7584 df-1st 7692 df-2nd 7693 df-supp 7834 df-wrecs 7950 df-recs 8011 df-rdg 8049 df-1o 8105 df-2o 8106 df-oadd 8109 df-omul 8110 df-er 8292 df-map 8411 df-pm 8412 df-ixp 8465 df-en 8513 df-dom 8514 df-sdom 8515 df-fin 8516 df-fsupp 8837 df-fi 8878 df-sup 8909 df-inf 8910 df-oi 8977 df-dju 9333 df-card 9371 df-acn 9374 df-pnf 10680 df-mnf 10681 df-xr 10682 df-ltxr 10683 df-le 10684 df-sub 10875 df-neg 10876 df-div 11301 df-nn 11642 df-2 11703 df-3 11704 df-4 11705 df-5 11706 df-6 11707 df-7 11708 df-8 11709 df-9 11710 df-n0 11901 df-xnn0 11971 df-z 11985 df-dec 12102 df-uz 12247 df-q 12352 df-rp 12393 df-xneg 12510 df-xadd 12511 df-xmul 12512 df-ioo 12745 df-ioc 12746 df-ico 12747 df-icc 12748 df-fz 12896 df-fzo 13037 df-fl 13165 df-mod 13241 df-seq 13373 df-exp 13433 df-fac 13637 df-bc 13666 df-hash 13694 df-shft 14429 df-cj 14461 df-re 14462 df-im 14463 df-sqrt 14597 df-abs 14598 df-limsup 14831 df-clim 14848 df-rlim 14849 df-sum 15046 df-ef 15424 df-sin 15426 df-cos 15427 df-pi 15429 df-struct 16488 df-ndx 16489 df-slot 16490 df-base 16492 df-sets 16493 df-ress 16494 df-plusg 16581 df-mulr 16582 df-starv 16583 df-sca 16584 df-vsca 16585 df-ip 16586 df-tset 16587 df-ple 16588 df-ds 16590 df-unif 16591 df-hom 16592 df-cco 16593 df-rest 16699 df-topn 16700 df-0g 16718 df-gsum 16719 df-topgen 16720 df-pt 16721 df-prds 16724 df-xrs 16778 df-qtop 16783 df-imas 16784 df-xps 16786 df-mre 16860 df-mrc 16861 df-acs 16863 df-mgm 17855 df-sgrp 17904 df-mnd 17915 df-submnd 17960 df-mulg 18228 df-cntz 18450 df-cmn 18911 df-psmet 20540 df-xmet 20541 df-met 20542 df-bl 20543 df-mopn 20544 df-fbas 20545 df-fg 20546 df-cnfld 20549 df-top 21505 df-topon 21522 df-topsp 21544 df-bases 21557 df-cld 21630 df-ntr 21631 df-cls 21632 df-nei 21709 df-lp 21747 df-perf 21748 df-cn 21838 df-cnp 21839 df-t1 21925 df-haus 21926 df-cmp 21998 df-tx 22173 df-hmeo 22366 df-fil 22457 df-fm 22549 df-flim 22550 df-flf 22551 df-xms 22933 df-ms 22934 df-tms 22935 df-cncf 23489 df-ovol 24068 df-vol 24069 df-mbf 24223 df-itg1 24224 df-itg2 24225 df-ibl 24226 df-itg 24227 df-0p 24274 df-ditg 24448 df-limc 24467 df-dv 24468 |
This theorem is referenced by: (None) |
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