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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 45861 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 5913 | . . . . . 6 ⊢ dom 𝐺 = dom ((ℝ D 𝐹) ↾ (-π(,)π)) |
6 | ioossre 13441 | . . . . . . . 8 ⊢ (-π(,)π) ⊆ ℝ | |
7 | fouriercn.dv | . . . . . . . . 9 ⊢ (𝜑 → (ℝ D 𝐹) ∈ (ℝ–cn→ℂ)) | |
8 | cncff 24907 | . . . . . . . . 9 ⊢ ((ℝ D 𝐹) ∈ (ℝ–cn→ℂ) → (ℝ D 𝐹):ℝ⟶ℂ) | |
9 | fdm 6739 | . . . . . . . . 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 4033 | . . . . . . 7 ⊢ (𝜑 → (-π(,)π) ⊆ dom (ℝ D 𝐹)) |
12 | ssdmres 6024 | . . . . . . 7 ⊢ ((-π(,)π) ⊆ dom (ℝ D 𝐹) ↔ dom ((ℝ D 𝐹) ↾ (-π(,)π)) = (-π(,)π)) | |
13 | 11, 12 | sylib 217 | . . . . . 6 ⊢ (𝜑 → dom ((ℝ D 𝐹) ↾ (-π(,)π)) = (-π(,)π)) |
14 | 5, 13 | eqtrid 2778 | . . . . 5 ⊢ (𝜑 → dom 𝐺 = (-π(,)π)) |
15 | 14 | difeq2d 4121 | . . . 4 ⊢ (𝜑 → ((-π(,)π) ∖ dom 𝐺) = ((-π(,)π) ∖ (-π(,)π))) |
16 | difid 4375 | . . . 4 ⊢ ((-π(,)π) ∖ (-π(,)π)) = ∅ | |
17 | 15, 16 | eqtrdi 2782 | . . 3 ⊢ (𝜑 → ((-π(,)π) ∖ dom 𝐺) = ∅) |
18 | 0fi 9082 | . . 3 ⊢ ∅ ∈ Fin | |
19 | 17, 18 | eqeltrdi 2834 | . 2 ⊢ (𝜑 → ((-π(,)π) ∖ dom 𝐺) ∈ Fin) |
20 | rescncf 24911 | . . . 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 7441 | . . 3 ⊢ (𝜑 → (dom 𝐺–cn→ℂ) = ((-π(,)π)–cn→ℂ)) |
24 | 21, 22, 23 | 3eltr4d 2841 | . 2 ⊢ (𝜑 → 𝐺 ∈ (dom 𝐺–cn→ℂ)) |
25 | pire 26489 | . . . . . 6 ⊢ π ∈ ℝ | |
26 | 25 | renegcli 11573 | . . . . 5 ⊢ -π ∈ ℝ |
27 | 25 | rexri 11324 | . . . . 5 ⊢ π ∈ ℝ* |
28 | icossre 13461 | . . . . 5 ⊢ ((-π ∈ ℝ ∧ π ∈ ℝ*) → (-π[,)π) ⊆ ℝ) | |
29 | 26, 27, 28 | mp2an 690 | . . . 4 ⊢ (-π[,)π) ⊆ ℝ |
30 | eldifi 4126 | . . . 4 ⊢ (𝑥 ∈ ((-π[,)π) ∖ dom 𝐺) → 𝑥 ∈ (-π[,)π)) | |
31 | 29, 30 | sselid 3977 | . . 3 ⊢ (𝑥 ∈ ((-π[,)π) ∖ dom 𝐺) → 𝑥 ∈ ℝ) |
32 | limcresi 25908 | . . . . . 6 ⊢ ((ℝ D 𝐹) limℂ 𝑥) ⊆ (((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (𝑥(,)+∞))) limℂ 𝑥) | |
33 | 4 | reseq1i 5987 | . . . . . . . 8 ⊢ (𝐺 ↾ (𝑥(,)+∞)) = (((ℝ D 𝐹) ↾ (-π(,)π)) ↾ (𝑥(,)+∞)) |
34 | resres 6004 | . . . . . . . 8 ⊢ (((ℝ D 𝐹) ↾ (-π(,)π)) ↾ (𝑥(,)+∞)) = ((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (𝑥(,)+∞))) | |
35 | 33, 34 | eqtr2i 2755 | . . . . . . 7 ⊢ ((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (𝑥(,)+∞))) = (𝐺 ↾ (𝑥(,)+∞)) |
36 | 35 | oveq1i 7436 | . . . . . 6 ⊢ (((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (𝑥(,)+∞))) limℂ 𝑥) = ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) |
37 | 32, 36 | sseqtri 4016 | . . . . 5 ⊢ ((ℝ D 𝐹) limℂ 𝑥) ⊆ ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) |
38 | 7 | adantr 479 | . . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → (ℝ D 𝐹) ∈ (ℝ–cn→ℂ)) |
39 | simpr 483 | . . . . . 6 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → 𝑥 ∈ ℝ) | |
40 | 38, 39 | cnlimci 25912 | . . . . 5 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((ℝ D 𝐹)‘𝑥) ∈ ((ℝ D 𝐹) limℂ 𝑥)) |
41 | 37, 40 | sselid 3977 | . . . 4 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((ℝ D 𝐹)‘𝑥) ∈ ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥)) |
42 | 41 | ne0d 4338 | . . 3 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) ≠ ∅) |
43 | 31, 42 | sylan2 591 | . 2 ⊢ ((𝜑 ∧ 𝑥 ∈ ((-π[,)π) ∖ dom 𝐺)) → ((𝐺 ↾ (𝑥(,)+∞)) limℂ 𝑥) ≠ ∅) |
44 | negpitopissre 26570 | . . . 4 ⊢ (-π(,]π) ⊆ ℝ | |
45 | eldifi 4126 | . . . 4 ⊢ (𝑥 ∈ ((-π(,]π) ∖ dom 𝐺) → 𝑥 ∈ (-π(,]π)) | |
46 | 44, 45 | sselid 3977 | . . 3 ⊢ (𝑥 ∈ ((-π(,]π) ∖ dom 𝐺) → 𝑥 ∈ ℝ) |
47 | limcresi 25908 | . . . . . 6 ⊢ ((ℝ D 𝐹) limℂ 𝑥) ⊆ (((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (-∞(,)𝑥))) limℂ 𝑥) | |
48 | 4 | reseq1i 5987 | . . . . . . . 8 ⊢ (𝐺 ↾ (-∞(,)𝑥)) = (((ℝ D 𝐹) ↾ (-π(,)π)) ↾ (-∞(,)𝑥)) |
49 | resres 6004 | . . . . . . . 8 ⊢ (((ℝ D 𝐹) ↾ (-π(,)π)) ↾ (-∞(,)𝑥)) = ((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (-∞(,)𝑥))) | |
50 | 48, 49 | eqtr2i 2755 | . . . . . . 7 ⊢ ((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (-∞(,)𝑥))) = (𝐺 ↾ (-∞(,)𝑥)) |
51 | 50 | oveq1i 7436 | . . . . . 6 ⊢ (((ℝ D 𝐹) ↾ ((-π(,)π) ∩ (-∞(,)𝑥))) limℂ 𝑥) = ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) |
52 | 47, 51 | sseqtri 4016 | . . . . 5 ⊢ ((ℝ D 𝐹) limℂ 𝑥) ⊆ ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) |
53 | 52, 40 | sselid 3977 | . . . 4 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((ℝ D 𝐹)‘𝑥) ∈ ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥)) |
54 | 53 | ne0d 4338 | . . 3 ⊢ ((𝜑 ∧ 𝑥 ∈ ℝ) → ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) ≠ ∅) |
55 | 46, 54 | sylan2 591 | . 2 ⊢ ((𝜑 ∧ 𝑥 ∈ ((-π(,]π) ∖ dom 𝐺)) → ((𝐺 ↾ (-∞(,)𝑥)) limℂ 𝑥) ≠ ∅) |
56 | eqid 2726 | . 2 ⊢ (topGen‘ran (,)) = (topGen‘ran (,)) | |
57 | ax-resscn 11217 | . . . . . . 7 ⊢ ℝ ⊆ ℂ | |
58 | 57 | a1i 11 | . . . . . 6 ⊢ (𝜑 → ℝ ⊆ ℂ) |
59 | 1, 58 | fssd 6747 | . . . . . . 7 ⊢ (𝜑 → 𝐹:ℝ⟶ℂ) |
60 | ssid 4002 | . . . . . . . 8 ⊢ ℝ ⊆ ℝ | |
61 | 60 | a1i 11 | . . . . . . 7 ⊢ (𝜑 → ℝ ⊆ ℝ) |
62 | dvcn 25945 | . . . . . . 7 ⊢ (((ℝ ⊆ ℂ ∧ 𝐹:ℝ⟶ℂ ∧ ℝ ⊆ ℝ) ∧ dom (ℝ D 𝐹) = ℝ) → 𝐹 ∈ (ℝ–cn→ℂ)) | |
63 | 58, 59, 61, 10, 62 | syl31anc 1370 | . . . . . 6 ⊢ (𝜑 → 𝐹 ∈ (ℝ–cn→ℂ)) |
64 | cncfcdm 24912 | . . . . . 6 ⊢ ((ℝ ⊆ ℂ ∧ 𝐹 ∈ (ℝ–cn→ℂ)) → (𝐹 ∈ (ℝ–cn→ℝ) ↔ 𝐹:ℝ⟶ℝ)) | |
65 | 58, 63, 64 | syl2anc 582 | . . . . 5 ⊢ (𝜑 → (𝐹 ∈ (ℝ–cn→ℝ) ↔ 𝐹:ℝ⟶ℝ)) |
66 | 1, 65 | mpbird 256 | . . . 4 ⊢ (𝜑 → 𝐹 ∈ (ℝ–cn→ℝ)) |
67 | eqid 2726 | . . . . . 6 ⊢ (TopOpen‘ℂfld) = (TopOpen‘ℂfld) | |
68 | 67 | tgioo2 24813 | . . . . . 6 ⊢ (topGen‘ran (,)) = ((TopOpen‘ℂfld) ↾t ℝ) |
69 | 67, 68, 68 | cncfcn 24924 | . . . . 5 ⊢ ((ℝ ⊆ ℂ ∧ ℝ ⊆ ℂ) → (ℝ–cn→ℝ) = ((topGen‘ran (,)) Cn (topGen‘ran (,)))) |
70 | 58, 58, 69 | syl2anc 582 | . . . 4 ⊢ (𝜑 → (ℝ–cn→ℝ) = ((topGen‘ran (,)) Cn (topGen‘ran (,)))) |
71 | 66, 70 | eleqtrd 2828 | . . 3 ⊢ (𝜑 → 𝐹 ∈ ((topGen‘ran (,)) Cn (topGen‘ran (,)))) |
72 | fouriercn.x | . . 3 ⊢ (𝜑 → 𝑋 ∈ ℝ) | |
73 | uniretop 24773 | . . . 4 ⊢ ℝ = ∪ (topGen‘ran (,)) | |
74 | 73 | cncnpi 23276 | . . 3 ⊢ ((𝐹 ∈ ((topGen‘ran (,)) Cn (topGen‘ran (,))) ∧ 𝑋 ∈ ℝ) → 𝐹 ∈ (((topGen‘ran (,)) CnP (topGen‘ran (,)))‘𝑋)) |
75 | 71, 72, 74 | syl2anc 582 | . 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 45865 | 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 205 ∧ wa 394 = wceq 1534 ∈ wcel 2099 ≠ wne 2930 ∖ cdif 3944 ∩ cin 3946 ⊆ wss 3947 ∅c0 4325 ↦ cmpt 5238 dom cdm 5684 ran crn 5685 ↾ cres 5686 ⟶wf 6552 ‘cfv 6556 (class class class)co 7426 Fincfn 8976 ℂcc 11158 ℝcr 11159 0cc0 11160 + caddc 11163 · cmul 11165 +∞cpnf 11297 -∞cmnf 11298 ℝ*cxr 11299 -cneg 11497 / cdiv 11923 ℕcn 12266 2c2 12321 ℕ0cn0 12526 (,)cioo 13380 (,]cioc 13381 [,)cico 13382 Σcsu 15692 sincsin 16067 cosccos 16068 πcpi 16070 TopOpenctopn 17438 topGenctg 17454 ℂfldccnfld 21345 Cn ccn 23222 CnP ccnp 23223 –cn→ccncf 24890 ∫citg 25641 limℂ climc 25885 D cdv 25886 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1906 ax-6 1964 ax-7 2004 ax-8 2101 ax-9 2109 ax-10 2130 ax-11 2147 ax-12 2167 ax-ext 2697 ax-rep 5292 ax-sep 5306 ax-nul 5313 ax-pow 5371 ax-pr 5435 ax-un 7748 ax-inf2 9686 ax-cc 10480 ax-cnex 11216 ax-resscn 11217 ax-1cn 11218 ax-icn 11219 ax-addcl 11220 ax-addrcl 11221 ax-mulcl 11222 ax-mulrcl 11223 ax-mulcom 11224 ax-addass 11225 ax-mulass 11226 ax-distr 11227 ax-i2m1 11228 ax-1ne0 11229 ax-1rid 11230 ax-rnegex 11231 ax-rrecex 11232 ax-cnre 11233 ax-pre-lttri 11234 ax-pre-lttrn 11235 ax-pre-ltadd 11236 ax-pre-mulgt0 11237 ax-pre-sup 11238 ax-addf 11239 |
This theorem depends on definitions: df-bi 206 df-an 395 df-or 846 df-3or 1085 df-3an 1086 df-tru 1537 df-fal 1547 df-ex 1775 df-nf 1779 df-sb 2061 df-mo 2529 df-eu 2558 df-clab 2704 df-cleq 2718 df-clel 2803 df-nfc 2878 df-ne 2931 df-nel 3037 df-ral 3052 df-rex 3061 df-rmo 3364 df-reu 3365 df-rab 3420 df-v 3464 df-sbc 3777 df-csb 3893 df-dif 3950 df-un 3952 df-in 3954 df-ss 3964 df-pss 3967 df-symdif 4244 df-nul 4326 df-if 4534 df-pw 4609 df-sn 4634 df-pr 4636 df-tp 4638 df-op 4640 df-uni 4916 df-int 4957 df-iun 5005 df-iin 5006 df-disj 5121 df-br 5156 df-opab 5218 df-mpt 5239 df-tr 5273 df-id 5582 df-eprel 5588 df-po 5596 df-so 5597 df-fr 5639 df-se 5640 df-we 5641 df-xp 5690 df-rel 5691 df-cnv 5692 df-co 5693 df-dm 5694 df-rn 5695 df-res 5696 df-ima 5697 df-pred 6314 df-ord 6381 df-on 6382 df-lim 6383 df-suc 6384 df-iota 6508 df-fun 6558 df-fn 6559 df-f 6560 df-f1 6561 df-fo 6562 df-f1o 6563 df-fv 6564 df-isom 6565 df-riota 7382 df-ov 7429 df-oprab 7430 df-mpo 7431 df-of 7692 df-ofr 7693 df-om 7879 df-1st 8005 df-2nd 8006 df-supp 8177 df-frecs 8298 df-wrecs 8329 df-recs 8403 df-rdg 8442 df-1o 8498 df-2o 8499 df-oadd 8502 df-omul 8503 df-er 8736 df-map 8859 df-pm 8860 df-ixp 8929 df-en 8977 df-dom 8978 df-sdom 8979 df-fin 8980 df-fsupp 9408 df-fi 9456 df-sup 9487 df-inf 9488 df-oi 9555 df-dju 9946 df-card 9984 df-acn 9987 df-pnf 11302 df-mnf 11303 df-xr 11304 df-ltxr 11305 df-le 11306 df-sub 11498 df-neg 11499 df-div 11924 df-nn 12267 df-2 12329 df-3 12330 df-4 12331 df-5 12332 df-6 12333 df-7 12334 df-8 12335 df-9 12336 df-n0 12527 df-xnn0 12599 df-z 12613 df-dec 12732 df-uz 12877 df-q 12987 df-rp 13031 df-xneg 13148 df-xadd 13149 df-xmul 13150 df-ioo 13384 df-ioc 13385 df-ico 13386 df-icc 13387 df-fz 13541 df-fzo 13684 df-fl 13814 df-mod 13892 df-seq 14024 df-exp 14084 df-fac 14293 df-bc 14322 df-hash 14350 df-shft 15074 df-cj 15106 df-re 15107 df-im 15108 df-sqrt 15242 df-abs 15243 df-limsup 15475 df-clim 15492 df-rlim 15493 df-sum 15693 df-ef 16071 df-sin 16073 df-cos 16074 df-pi 16076 df-struct 17151 df-sets 17168 df-slot 17186 df-ndx 17198 df-base 17216 df-ress 17245 df-plusg 17281 df-mulr 17282 df-starv 17283 df-sca 17284 df-vsca 17285 df-ip 17286 df-tset 17287 df-ple 17288 df-ds 17290 df-unif 17291 df-hom 17292 df-cco 17293 df-rest 17439 df-topn 17440 df-0g 17458 df-gsum 17459 df-topgen 17460 df-pt 17461 df-prds 17464 df-xrs 17519 df-qtop 17524 df-imas 17525 df-xps 17527 df-mre 17601 df-mrc 17602 df-acs 17604 df-mgm 18635 df-sgrp 18714 df-mnd 18730 df-submnd 18776 df-mulg 19064 df-cntz 19313 df-cmn 19782 df-psmet 21337 df-xmet 21338 df-met 21339 df-bl 21340 df-mopn 21341 df-fbas 21342 df-fg 21343 df-cnfld 21346 df-top 22890 df-topon 22907 df-topsp 22929 df-bases 22943 df-cld 23017 df-ntr 23018 df-cls 23019 df-nei 23096 df-lp 23134 df-perf 23135 df-cn 23225 df-cnp 23226 df-t1 23312 df-haus 23313 df-cmp 23385 df-tx 23560 df-hmeo 23753 df-fil 23844 df-fm 23936 df-flim 23937 df-flf 23938 df-xms 24320 df-ms 24321 df-tms 24322 df-cncf 24892 df-ovol 25487 df-vol 25488 df-mbf 25642 df-itg1 25643 df-itg2 25644 df-ibl 25645 df-itg 25646 df-0p 25693 df-ditg 25870 df-limc 25889 df-dv 25890 |
This theorem is referenced by: (None) |
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