{"id":"lem:snormEssSup_eq_sSup_snorm","label":"snormEssSup_eq_sSup_snorm","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":[],"nlp_text":"Let \\(f\\) be measurable and the measure \\(\\mu \\) be \\(\\sigma \\)-finite. Then \\[ \\| f\\| _{L^\\infty } = \\sup _{\\| g\\| _{L^1} \\leq 1, \\ g \\text{ simple}} \\| fg \\| _{L^1}. \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/MeasureTheory.snormEssSup_eq_sSup_snorm","latex_link":"chap-interpolation.html#lem:snormEssSup_eq_sSup_snorm","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/MeasureTheory.snormEssSup_eq_sSup_snorm","lean_decl_name":"MeasureTheory.snormEssSup_eq_sSup_snorm","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"source_repo":"remote_github","source_path":"https://raw.githubusercontent.com/fpvandoorn/BonnAnalysis/f3acd7b6e64e9949e697d595d495e01dc4c3dbf9/BonnAnalysis/ComplexInterpolation.lean","lean4_code":"lemma snormEssSup_eq_sSup_snorm [SigmaFinite μ] (f : α → ℂ) (hf : Measurable f)\n(hf' : sSup {x |∃ g : SimpleFunc α ℂ, snorm g 1 μ ≤ 1 ∧\nx = snorm (f * (g : α → ℂ)) 1 μ} < ⊤):\nsnormEssSup f μ = sSup {x |∃ g : SimpleFunc α ℂ, snorm g 1 μ ≤ 1\n∧ x = snorm (f * (g : α → ℂ)) 1 μ} := by\n apply le_antisymm ?_\n . apply sSup_le\n intro s ⟨g, hg₁, hg₂⟩\n rw [hg₂, mul_comm]\n simp [snorm, snorm']\n apply le_trans (lintegral_norm_mul_le_one_top _ (by measurability))\n apply mul_le_of_le_one_of_le hg₁ (by simp [snorm])\n . set M := sSup {x |∃ g : SimpleFunc α ℂ, snorm g 1 μ ≤ 1 ∧\n x = snorm (f * (g : α → ℂ)) 1 μ}\n apply essSup_le_of_ae_le\n simp only [EventuallyLE, eventually_iff, mem_ae_iff]\n by_contra h\n\n have aux1 : ∃ B : Set α, MeasurableSet B ∧ B ⊆ {x | ‖f x‖₊ ≤ M}ᶜ ∧ 0 < μ B ∧ μ B < ⊤ := by\n apply Measure.exists_subset_measure_lt_top (MeasurableSet.compl _) ((ne_eq _ _) ▸ h).bot_lt\n convert hf.ennnorm measurableSet_Iic\n rcases aux1 with ⟨B, hB⟩\n\n let g : SimpleFunc α ℂ := {\n toFun := B.indicator (fun _ ↦ ((μ B)⁻¹.toReal : ℂ))\n measurableSet_fiber' := by\n intro x\n simp [indicator_preimage]\n rcases eq_or_ne x ((μ B)⁻¹.toReal : ℂ) with (H | H)\n simp [H]\n apply MeasurableSet.ite hB.1 (by simp only [MeasurableSet.univ, M])\n apply measurableSet_preimage measurable_zero (MeasurableSet.singleton _)\n apply MeasurableSet.ite hB.1 _ (measurableSet_preimage measurable_zero\n (MeasurableSet.singleton _))\n rw [preimage_const_of_not_mem]\n apply MeasurableSet.empty\n rw [mem_singleton_iff]\n exact H.symm\n finite_range' := by\n have : range (B.indicator fun _ ↦ ((μ B)⁻¹.toReal : ℂ))\n ⊆ {0, ((μ B)⁻¹.toReal : ℂ)} := by\n intro x\n rw [Set.mem_range_indicator]\n simp\n rintro (h | h)\n exact Or.intro_left _ h.1\n exact Or.intro_right _ h.2.symm\n apply Set.Finite.subset _ this\n simp only [finite_singleton, Finite.insert]\n }\n\n have aux_μB : (μ B)⁻¹ = ‖(μ B)⁻¹.toReal‖₊ := by\n have : (μ B)⁻¹ < ⊤ := by simp [hB.2.2.1]\n generalize (μ B)⁻¹ = y at this -- better solution???\n cases y\n simp only [lt_self_iff_false] at this\n simp only [coe_toReal, nnnorm_eq]\n\n have : ¬ (M < snorm (f * (g : α → ℂ)) 1 μ) := by\n simp\n apply le_sSup\n use g\n constructor\n simp [snorm, snorm', lintegral_indicator_const]\n have : ∫⁻ (a : α), (B.indicator (fun _ ↦ (μ B)⁻¹) a) ∂ μ ≤ 1 := by\n rw [lintegral_indicator_const hB.1,\n ENNReal.inv_mul_cancel hB.2.2.1.ne.symm hB.2.2.2.ne]\n convert this\n rename α => x\n by_cases hx : x ∈ B\n simp [indicator_of_mem hx, aux_μB.symm]\n simp [indicator_of_not_mem hx]\n rfl\n\n apply this\n calc M = ∫⁻ _ in B, (μ B)⁻¹ * M ∂ μ := by {\n rw [setLIntegral_const, mul_assoc, mul_comm M, ← mul_assoc,\n ENNReal.inv_mul_cancel hB.2.2.1.ne.symm hB.2.2.2.ne, one_mul]\n }\n _ < ∫⁻ x in B, (μ B)⁻¹ * ‖f x‖₊ ∂ μ := by\n apply setLIntegral_strict_mono hB.1 hB.2.2.1.ne.symm (hf.ennnorm.const_mul _)\n rw [setLIntegral_const]\n apply mul_ne_top (mul_ne_top (ENNReal.inv_ne_top.mpr\n hB.2.2.1.ne.symm) hf'.ne) hB.2.2.2.ne\n apply eventually_of_forall\n intro x hx\n rw [ENNReal.mul_lt_mul_left (ENNReal.inv_ne_zero.mpr hB.2.2.2.ne)\n (ENNReal.inv_ne_top.mpr hB.2.2.1.ne.symm)]\n convert hB.2.1 hx\n simp only [mem_compl_iff, mem_setOf_eq, not_le]\n _ = ∫⁻ x : α, B.indicator (fun a ↦ ‖f a‖₊ * ‖(fun _ ↦ ((μ B)⁻¹.toReal : ℂ)) a‖₊) x ∂μ := by\n rw [lintegral_indicator _ hB.1]\n simp [mul_comm]\n congr with x; congr\n _ = snorm (f * B.indicator fun _ ↦ ((μ B)⁻¹.toReal : ℂ)) 1 μ := by\n simp [snorm, snorm']\n congr with x\n by_cases hx : x ∈ B\n simp only [indicator_of_mem hx, nnnorm_real]\n simp only [indicator_of_not_mem hx, nnnorm_zero, ENNReal.coe_zero, mul_zero]","line":1025,"end_line":1124,"proof_status":"formalized"} {"id":"a0000000211","label":"a0000000211","background_color":"white","border_color":"blue","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":[],"nlp_text":"For \\(\\lambda {\\gt} -d\\), Let \\(H_\\lambda \\) be the tempered distribution associated to \\(|x|^\\lambda \\in L^1_{loc}\\). If \\(-d {\\lt} \\lambda {\\lt} 0\\) then \\[ \\widehat{H_\\lambda } = c_\\lambda H_{-d-\\lambda } \\]","doc_url":null,"latex_link":"sect0001.html#a0000000211","lean_link":null,"lean_decl_name":"a0000000211","kind_description":"theorems and lemmas","status_from_color":"ready_to_formalize","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"a0000000168","label":"a0000000168","background_color":"#A3D6FF","border_color":"blue","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":[],"nlp_text":"Then \\(C^\\infty (\\mathbb {R}^d)\\) is dense in \\(\\mathcal{D}'(\\mathbb {R}^d)\\).","doc_url":null,"latex_link":"sect0001.html#a0000000168","lean_link":null,"lean_decl_name":"a0000000168","kind_description":"theorems and lemmas","status_from_color":"ready_to_formalize","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"lem:hausdorff_young","label":"hausdorff_young","background_color":"white","border_color":"blue","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["thm:riesz_interpolation"],"nlp_text":"Let \\(X=[0,2\\pi ]\\) with normalized Lebesgue measure \\(\\frac{d\\theta }{2\\pi }\\) and let \\(Y=\\mathbb {Z}\\) with counting measure.Consider the operator \\(T: f \\mapsto \\{ a_n\\} _{n\\in \\mathbb {Z}}\\) where \\[ a_n = \\frac{1}{2\\pi } \\int _0^{2\\pi } f(\\theta ) e^{-in\\theta } d\\theta \\]","doc_url":null,"latex_link":"chap-interpolation.html#lem:hausdorff_young","lean_link":null,"lean_decl_name":"hausdorff_young","kind_description":"theorems and lemmas","status_from_color":"ready_to_formalize","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"thm:fourier-inversion-L1","label":"fourier-inversion-L1","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["lem:fourier-multiplication","thm:kernel-approximation"],"nlp_text":"Let \\(f\\in L^1(V,E)\\). If \\(\\widehat f\\in L^1(V,E)\\), then \\(\\mathcal F^{-1}\\mathcal Ff=f\\).","doc_url":null,"latex_link":"chap-plancherel.html#thm:fourier-inversion-L1","lean_link":null,"lean_decl_name":"fourier-inversion-L1","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"lem:fourier-gaussian","label":"fourier-gaussian","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["lem:fourier-prop"],"nlp_text":"Let \\(x\\in V\\) and \\(\\delta {\\gt}0\\). Define the modulated Gaussian \\[ u_{x,\\delta }(y):V\\to \\mathbb {C},\\quad y\\mapsto e^{-\\delta \\pi |y|^2}e^{2\\pi i x y}. \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/fourierIntegral_gaussian_innerProductSpace'","latex_link":"chap-plancherel.html#lem:fourier-gaussian","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/fourierIntegral_gaussian_innerProductSpace'","lean_decl_name":"fourierIntegral_gaussian_innerProductSpace'","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"source_repo":"remote_github","source_path":"https://raw.githubusercontent.com/leanprover-community/mathlib4/b387c548d1dc9cea5c5fcb71e5b3370cca1a04cc/Mathlib/Analysis/SpecialFunctions/Gaussian/FourierTransform.lean","lean4_code":"theorem _root_.fourierIntegral_gaussian_innerProductSpace' (hb : 0 < b.re) (x w : V) :\n 𝓕 (fun v ↦ cexp (- b * ‖v‖^2 + 2 * π * Complex.I * ⟪x, v⟫)) w =\n (π / b) ^ (FiniteDimensional.finrank ℝ V / 2 : ℂ) * cexp (-π ^ 2 * ‖x - w‖ ^ 2 / b) := by\n simp only [neg_mul, fourierIntegral_eq', ofReal_neg, ofReal_mul, ofReal_ofNat,\n smul_eq_mul, ← Complex.exp_add, real_inner_comm w]\n convert integral_cexp_neg_mul_sq_norm_add hb (2 * π * Complex.I) (x - w) using 3 with v\n · congr 1\n simp [inner_sub_left]\n ring\n · have : b ≠ 0 := by contrapose! hb; rw [hb, zero_re]\n field_simp [mul_pow]\n ring","line":369,"end_line":380,"proof_status":"formalized"} {"id":"thm:plancherel","label":"plancherel","background_color":"#A3D6FF","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["lem:fourier-gaussian","lem:fourier-multiplication","thm:kernel-approximation"],"nlp_text":"Suppose that \\(f : V \\to E\\) is in \\(L^1(V,E)\\cap L^2(V,E)\\) and let \\(\\widehat{f}\\) be the Fourier transform of \\(f\\). Then \\(\\widehat{f},\\check{f}\\in L^2(V,E)\\) and \\[ \\| \\widehat{f}\\| _{L^2} = \\| f\\| _{L^2}=\\| \\check f\\| _{L^2}. \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/MeasureTheory.memℒp_fourierIntegral","latex_link":"chap-plancherel.html#thm:plancherel","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/MeasureTheory.memℒp_fourierIntegral","lean_decl_name":"MeasureTheory.memℒp_fourierIntegral","kind_description":"theorems and lemmas","status_from_color":"ready_to_formalize","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"source_repo":"remote_github","source_path":"https://raw.githubusercontent.com/fpvandoorn/BonnAnalysis/f3acd7b6e64e9949e697d595d495e01dc4c3dbf9/BonnAnalysis/Plancherel.lean","lean4_code":"theorem memℒp_fourierIntegral {f : V → ℂ} (hf : Integrable f) (h2f : Memℒp f 2) :\n Memℒp (𝓕 f) 2 := by\n unfold Memℒp; constructor\n · apply Continuous.aestronglyMeasurable\n exact VectorFourier.fourierIntegral_continuous continuous_fourierChar\n (by simp only [innerₗ_apply]; exact continuous_inner) hf\n · rw [snorm_fourierIntegral hf h2f]\n exact h2f.2","line":473,"end_line":480,"proof_status":"statement_formalized"} {"id":"lem:fourier12-cauchy","label":"fourier12-cauchy","background_color":"white","border_color":"black","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["thm:plancherel","lem:L12-dense"],"nlp_text":"Let \\(f\\in L^2(V,E)\\) and \\((f_n)_n\\subset L^1(V,E)\\cap L^2(V,E)\\) a sequence with \\(f_n\\xrightarrow [L^2]{}f\\). Then \\((\\widehat f_n)_n\\) is a Cauchy sequence, hence converges in \\(L^2(V,E)\\).","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","latex_link":"chap-plancherel.html#lem:fourier12-cauchy","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","lean_decl_name":"","kind_description":"theorems and lemmas","status_from_color":"incomplete","lookup_in_mathlib4v4.22.0":false,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"def:invFourier-L2","label":"invFourier-L2","background_color":"white","border_color":"black","kind":"box","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["lem:fourier12-cauchy"],"nlp_text":"Define analogously \\(\\mathcal F^{-1}f:=\\check f:=\\lim _{n\\to \\infty }\\check f_n\\), if \\(f_n\\xrightarrow [L^2]{}f\\in L^2(V,E)\\) with \\((f_n)_n\\subset L^1(V,E)\\cap L^2(V,E)\\). By the same arguments as above, this is well-defined.","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","latex_link":"chap-plancherel.html#def:invFourier-L2","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","lean_decl_name":"","kind_description":"definitions","status_from_color":"incomplete","lookup_in_mathlib4v4.22.0":false,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"def:fourier-L2","label":"fourier-L2","background_color":"white","border_color":"black","kind":"box","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["lem:fourier12-cauchy"],"nlp_text":"Let \\(f\\in L^2(V,E)\\) and take a sequence \\((f_n)_n\\subset L^1(V,E)\\cap L^2(V,E)\\) with \\(f_n\\xrightarrow [L^2]{}f\\). Set \\[ \\mathcal Ff:=\\widehat f:=\\lim _{n\\to \\infty }\\widehat{f_n}, \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","latex_link":"chap-plancherel.html#def:fourier-L2","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","lean_decl_name":"","kind_description":"definitions","status_from_color":"incomplete","lookup_in_mathlib4v4.22.0":false,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"lem:fourier-bounded","label":"fourier-bounded","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["def:fourier-transform"],"nlp_text":"Let \\(f\\in L^1(V,E)\\). Then its Fourier transform \\(\\widehat f\\) is well-defined and bounded. In particular, the Fourier transform defines a map \\(\\mathcal F:L^1(V,E)\\to L^\\infty (V,E)\\).","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/VectorFourier.fourierIntegral_convergent_iff","latex_link":"chap-plancherel.html#lem:fourier-bounded","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/VectorFourier.fourierIntegral_convergent_iff","lean_decl_name":"VectorFourier.fourierIntegral_convergent_iff","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":true,"source_repo":"mathlib","source_path":"./Mathlib/Analysis/Fourier/FourierTransform.lean","lean4_code":"theorem fourierIntegral_convergent_iff (he : Continuous e)\n (hL : Continuous fun p : V × W ↦ L p.1 p.2) {f : V → E} (w : W) :\n Integrable (fun v : V ↦ e (-L v w) • f v) μ ↔ Integrable f μ := by\n -- first prove one-way implication\n have aux {g : V → E} (hg : Integrable g μ) (x : W) :\n Integrable (fun v : V ↦ e (-L v x) • g v) μ := by\n have c : Continuous fun v ↦ e (-L v x) := he.comp (hL.comp (.prodMk_left _)).neg\n simp_rw [← integrable_norm_iff (c.aestronglyMeasurable.smul hg.1), Circle.norm_smul]\n exact hg.norm\n -- then use it for both directions\n refine ⟨fun hf ↦ ?_, fun hf ↦ aux hf w⟩\n have := aux hf (-w)\n simp_rw [← mul_smul (e _) (e _) (f _), ← e.map_add_eq_mul, LinearMap.map_neg, neg_add_cancel,\n e.map_zero_eq_one, one_smul] at this -- the `(e _)` speeds up elaboration considerably\n exact this\n\n","line":124,"end_line":139,"proof_status":"formalized"} {"id":"a0000000173","label":"a0000000173","background_color":"#A3D6FF","border_color":"blue","kind":"box","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":[],"nlp_text":"For a multiindex \\(\\alpha \\) and a distribution \\(F\\) define the distribution \\[ \\partial ^\\alpha F (\\phi ) = (-1)^{|\\alpha |}(F \\partial ^\\alpha \\phi ) \\]","doc_url":null,"latex_link":"sect0001.html#a0000000173","lean_link":null,"lean_decl_name":"a0000000173","kind_description":"definitions","status_from_color":"ready_to_formalize","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"a0000000191","label":"a0000000191","background_color":"#A3D6FF","border_color":"blue","kind":"box","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":[],"nlp_text":"The fourier transformation is a continuous bijection \\begin{align*} \\mathcal{S}& \\to \\mathcal{S}\\\\ \\phi & \\mapsto \\hat\\phi = (\\xi \\mapsto \\int _{\\mathbb {R}^d} \\phi (x) e^{-2\\pi i x \\xi } \\ \\mathrm{d} x) \\end{align*}","doc_url":null,"latex_link":"sect0001.html#a0000000191","lean_link":null,"lean_decl_name":"a0000000191","kind_description":"definitions","status_from_color":"ready_to_formalize","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"a0000000195","label":"a0000000195","background_color":"#A3D6FF","border_color":"blue","kind":"box","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":[],"nlp_text":"Define \\[ \\hat F (\\phi ) = F (\\hat\\phi ) \\]","doc_url":null,"latex_link":"sect0001.html#a0000000195","lean_link":null,"lean_decl_name":"a0000000195","kind_description":"definitions","status_from_color":"ready_to_formalize","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"lem:fourier-cont","label":"fourier-cont","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["def:fourier-transform"],"nlp_text":"Let \\(f\\in L^1(V,E)\\). Then \\(\\widehat f\\) is continuous.","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/VectorFourier.fourierIntegral_continuous","latex_link":"chap-plancherel.html#lem:fourier-cont","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/VectorFourier.fourierIntegral_continuous","lean_decl_name":"VectorFourier.fourierIntegral_continuous","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":true,"source_repo":"mathlib","source_path":"./Mathlib/Analysis/Fourier/FourierTransform.lean","lean4_code":"theorem fourierIntegral_continuous [FirstCountableTopology W] (he : Continuous e)\n (hL : Continuous fun p : V × W ↦ L p.1 p.2) {f : V → E} (hf : Integrable f μ) :\n Continuous (fourierIntegral e μ L f) := by\n apply continuous_of_dominated\n · exact fun w ↦ ((fourierIntegral_convergent_iff he hL w).2 hf).1\n · exact fun w ↦ ae_of_all _ fun v ↦ le_of_eq (Circle.norm_smul _ _)\n · exact hf.norm\n · refine ae_of_all _ fun v ↦ (he.comp ?_).smul continuous_const\n exact (hL.comp (.prodMk_right _)).neg\n\nend Continuous\n\nsection Fubini\n\nvariable [TopologicalSpace 𝕜] [IsTopologicalRing 𝕜] [TopologicalSpace V] [BorelSpace V]\n [TopologicalSpace W] [MeasurableSpace W] [BorelSpace W]\n {e : AddChar 𝕜 𝕊} {μ : Measure V} {L : V →ₗ[𝕜] W →ₗ[𝕜] 𝕜}\n {ν : Measure W} [SigmaFinite μ] [SigmaFinite ν] [SecondCountableTopology V]\n\nvariable [CompleteSpace E] [CompleteSpace F]\n\n/-- The Fourier transform satisfies `∫ 𝓕 f * g = ∫ f * 𝓕 g`, i.e., it is self-adjoint.\nVersion where the multiplication is replaced by a general bilinear form `M`. -/\n","line":151,"end_line":173,"proof_status":"formalized"} {"id":"lem:fourier-multiplication","label":"fourier-multiplication","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["lem:fourier-cont"],"nlp_text":"Let \\(f,g\\in L^1(V,E)\\). Then \\[ \\int _WM(\\widehat f(w),g(w))\\, d\\nu (w)=\\int _VM(f(v),\\widehat g(v))\\, d\\mu (v). \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/VectorFourier.integral_bilin_fourierIntegral_eq_flip","latex_link":"chap-plancherel.html#lem:fourier-multiplication","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/VectorFourier.integral_bilin_fourierIntegral_eq_flip","lean_decl_name":"VectorFourier.integral_bilin_fourierIntegral_eq_flip","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":true,"source_repo":"mathlib","source_path":"./Mathlib/Analysis/Fourier/FourierTransform.lean","lean4_code":"theorem integral_bilin_fourierIntegral_eq_flip\n {f : V → E} {g : W → F} (M : E →L[ℂ] F →L[ℂ] G) (he : Continuous e)\n (hL : Continuous fun p : V × W ↦ L p.1 p.2) (hf : Integrable f μ) (hg : Integrable g ν) :\n ∫ ξ, M (fourierIntegral e μ L f ξ) (g ξ) ∂ν =\n ∫ x, M (f x) (fourierIntegral e ν L.flip g x) ∂μ := by\n by_cases hG : CompleteSpace G; swap; · simp [integral, hG]\n calc\n _ = ∫ ξ, M.flip (g ξ) (∫ x, e (-L x ξ) • f x ∂μ) ∂ν := rfl\n _ = ∫ ξ, (∫ x, M.flip (g ξ) (e (-L x ξ) • f x) ∂μ) ∂ν := by\n congr with ξ\n apply (ContinuousLinearMap.integral_comp_comm _ _).symm\n exact (fourierIntegral_convergent_iff he hL _).2 hf\n _ = ∫ x, (∫ ξ, M.flip (g ξ) (e (-L x ξ) • f x) ∂ν) ∂μ := by\n rw [integral_integral_swap]\n have : Integrable (fun (p : W × V) ↦ ‖M‖ * (‖g p.1‖ * ‖f p.2‖)) (ν.prod μ) :=\n (hg.norm.mul_prod hf.norm).const_mul _\n apply this.mono\n · -- This proof can be golfed but becomes very slow; breaking it up into steps\n -- speeds up compilation.\n change AEStronglyMeasurable (fun p : W × V ↦ (M (e (-(L p.2) p.1) • f p.2) (g p.1))) _\n have A : AEStronglyMeasurable (fun (p : W × V) ↦ e (-L p.2 p.1) • f p.2) (ν.prod μ) := by\n refine (Continuous.aestronglyMeasurable ?_).smul hf.1.comp_snd\n exact he.comp (hL.comp continuous_swap).neg\n have A' : AEStronglyMeasurable (fun p ↦ (g p.1, e (-(L p.2) p.1) • f p.2) : W × V → F × E)\n (Measure.prod ν μ) := hg.1.comp_fst.prodMk A\n have B : Continuous (fun q ↦ M q.2 q.1 : F × E → G) := M.flip.continuous₂\n apply B.comp_aestronglyMeasurable A' -- `exact` works, but `apply` is 10x faster!\n · filter_upwards with ⟨ξ, x⟩\n rw [Function.uncurry_apply_pair, Submonoid.smul_def, (M.flip (g ξ)).map_smul,\n ← Submonoid.smul_def, Circle.norm_smul, ContinuousLinearMap.flip_apply,\n norm_mul, norm_norm M, norm_mul, norm_norm, norm_norm, mul_comm (‖g _‖), ← mul_assoc]\n exact M.le_opNorm₂ (f x) (g ξ)\n _ = ∫ x, (∫ ξ, M (f x) (e (-L.flip ξ x) • g ξ) ∂ν) ∂μ := by\n simp only [ContinuousLinearMap.flip_apply, ContinuousLinearMap.map_smul_of_tower,\n ContinuousLinearMap.coe_smul', Pi.smul_apply, LinearMap.flip_apply]\n _ = ∫ x, M (f x) (∫ ξ, e (-L.flip ξ x) • g ξ ∂ν) ∂μ := by\n congr with x\n apply ContinuousLinearMap.integral_comp_comm\n apply (fourierIntegral_convergent_iff he _ _).2 hg\n exact hL.comp continuous_swap\n\n/-- The Fourier transform satisfies `∫ 𝓕 f * g = ∫ f * 𝓕 g`, i.e., it is self-adjoint. -/\n","line":174,"end_line":215,"proof_status":"formalized"} {"id":"thm:fourier-inversion","label":"fourier-inversion","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["lem:fourier-multiplication","thm:kernel-approximation"],"nlp_text":"Let \\(f:V\\to E\\) be integrable and continuous. Assume \\(\\widehat f\\) is integrable as well. Then \\[ \\mathcal F^{-1}\\mathcal F f=f. \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/MeasureTheory.Integrable.fourier_inversion","latex_link":"chap-plancherel.html#thm:fourier-inversion","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/MeasureTheory.Integrable.fourier_inversion","lean_decl_name":"MeasureTheory.Integrable.fourier_inversion","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"source_repo":"remote_github","source_path":"https://raw.githubusercontent.com/leanprover-community/mathlib4/b387c548d1dc9cea5c5fcb71e5b3370cca1a04cc/Mathlib/Analysis/Fourier/Inversion.lean","lean4_code":"theorem MeasureTheory.Integrable.fourier_inversion\n (hf : Integrable f) (h'f : Integrable (𝓕 f)) {v : V}\n (hv : ContinuousAt f v) : 𝓕⁻ (𝓕 f) v = f v :=\n tendsto_nhds_unique (Real.tendsto_integral_gaussian_smul hf h'f v)\n (Real.tendsto_integral_gaussian_smul' hf hv)","line":159,"end_line":163,"proof_status":"formalized"} {"id":"thm:fourier2-properties","label":"fourier2-properties","background_color":"white","border_color":"black","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["thm:fourier-inversion","def:invFourier-L2","lem:fourier2-welldef"],"nlp_text":"Plancherel’s Theorem, the inversion formula, and the properties of Lemma 2.5 hold for the Fourier transform on \\(L^2(V,E)\\) as well.","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","latex_link":"chap-plancherel.html#thm:fourier2-properties","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","lean_decl_name":"","kind_description":"theorems and lemmas","status_from_color":"incomplete","lookup_in_mathlib4v4.22.0":false,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"lem:fourier-prop","label":"fourier-prop","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["def:fourier-transform"],"nlp_text":"Lef \\(f,g\\in L^1(V,E)\\), \\(t\\in \\mathbb {R}\\) and \\(a,b\\in \\mathbb {C}\\). The Fourier transform satisfies the following elementary properties: \\(\\mathcal F(af+bg)=a\\mathcal Ff+b\\mathcal Fg\\)(Linearity) \\(\\mathcal F(f(x-t)) = e^{-2\\pi i ty}\\mathcal F f(y)\\)(Shifting) \\(\\mathcal F(f(tx)) = \\frac1{|t|}\\mathcal F f(\\frac yt)\\)(Scaling) If \\(E\\) admits a conjugation, then \\(\\mathcal F(\\overline{f(x)}) = \\overline{\\mathcal Ff(-y)}\\)(Conjugation) Define the convolution of \\(f\\) and \\(g\\) w.r.t. a bilinear map \\(M:E\\times E\\to F\\) as \\[ (f\\ast _Mg)(w):=\\int _VM(f(v),g(w-v))\\, d\\mu (v). \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/VectorFourier.fourierIntegral_add","latex_link":"chap-plancherel.html#lem:fourier-prop","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/VectorFourier.fourierIntegral_add","lean_decl_name":"VectorFourier.fourierIntegral_add","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":true,"source_repo":"mathlib","source_path":"./Mathlib/Analysis/Fourier/FourierTransform.lean","lean4_code":"theorem fourierIntegral_add (he : Continuous e) (hL : Continuous fun p : V × W ↦ L p.1 p.2)\n {f g : V → E} (hf : Integrable f μ) (hg : Integrable g μ) :\n fourierIntegral e μ L (f + g) = fourierIntegral e μ L f + fourierIntegral e μ L g := by\n ext1 w\n dsimp only [Pi.add_apply, fourierIntegral]\n simp_rw [smul_add]\n rw [integral_add]\n · exact (fourierIntegral_convergent_iff he hL w).2 hf\n · exact (fourierIntegral_convergent_iff he hL w).2 hg\n\n/-- The Fourier integral of an `L^1` function is a continuous function. -/\n","line":140,"end_line":150,"proof_status":"formalized"} {"id":"lem:fourier2-welldef","label":"fourier2-welldef","background_color":"white","border_color":"black","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["def:fourier-L2"],"nlp_text":"This is well-defined: By Lemma 2.15, the limit exists. Further it does not depend on the choice of sequence \\((f_n)_n\\). If \\(f\\in L^1(V,E)\\cap L^2(V,E)\\), this definition agrees with the Fourier transform on \\(L^1(V,E)\\).","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","latex_link":"chap-plancherel.html#lem:fourier2-welldef","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/","lean_decl_name":"","kind_description":"theorems and lemmas","status_from_color":"incomplete","lookup_in_mathlib4v4.22.0":false,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"thm:fourier-is-l2-linear","label":"fourier-is-l2-linear","background_color":"white","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["thm:fourier2-properties"],"nlp_text":"The Fourier transform induces a continuous linear map \\(L^2(V,E) \\to L^2(V,E)\\).","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/MeasureTheory.fourierIntegralL2","latex_link":"chap-plancherel.html#thm:fourier-is-l2-linear","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/MeasureTheory.fourierIntegralL2","lean_decl_name":"MeasureTheory.fourierIntegralL2","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"source_repo":"remote_github","source_path":"https://raw.githubusercontent.com/fpvandoorn/BonnAnalysis/f3acd7b6e64e9949e697d595d495e01dc4c3dbf9/BonnAnalysis/Plancherel.lean","lean4_code":"def fourierIntegralL2 : (V →₂[volume] ℂ) →L[ℝ] (V →₂[volume] ℂ) :=\n sorry","line":619,"end_line":620,"proof_status":"formalized"} {"id":"lem:weierstrass-kernel","label":"weierstrass-kernel","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":[],"nlp_text":"Let \\(K_\\delta (v)=\\delta ^{-n/2}e^{-\\pi |v|^2/\\delta }\\) as in Lemma 2.6. This is a good kernel, called the Weierstrass kernel, satisfying \\[ \\int _{V}K_\\delta (x)\\, dx= 1\\quad \\text{and}\\quad \\int _{|x|{\\gt}\\eta }K_\\delta (x)\\, dx\\xrightarrow {\\delta \\to 0}0\\quad \\text{for all }\\eta {\\gt}0. \\]","doc_url":null,"latex_link":"chap-plancherel.html#lem:weierstrass-kernel","lean_link":null,"lean_decl_name":"weierstrass-kernel","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"proof_status":"nlp_only"} {"id":"thm:kernel-approximation","label":"kernel-approximation","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":["lem:weierstrass-kernel"],"nlp_text":"Let \\(f:V\\to E\\) be integrable. Let \\(K_\\delta \\) be the Weierstrass kernel from Lemma 2.7, or indeed any family of functions satisfying the conditions of Lemma 2.7. Then \\[ (K_\\delta \\ast f)(x):=\\int _V K_\\delta (y)f(x-y)\\, d\\mu (y)\\xrightarrow {\\delta \\to 0}f(x) \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/Real.tendsto_integral_gaussian_smul'","latex_link":"chap-plancherel.html#thm:kernel-approximation","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/Real.tendsto_integral_gaussian_smul'","lean_decl_name":"Real.tendsto_integral_gaussian_smul'","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"source_repo":"remote_github","source_path":"https://raw.githubusercontent.com/leanprover-community/mathlib4/b387c548d1dc9cea5c5fcb71e5b3370cca1a04cc/Mathlib/Analysis/Fourier/Inversion.lean","lean4_code":"lemma tendsto_integral_gaussian_smul' (hf : Integrable f) {v : V} (h'f : ContinuousAt f v) :\n Tendsto (fun (c : ℝ) ↦\n ∫ w : V, ((π * c : ℂ) ^ (finrank ℝ V / 2 : ℂ) * cexp (-π ^ 2 * c * ‖v - w‖ ^ 2)) • f w)\n atTop (𝓝 (f v)) := by\n let φ : V → ℝ := fun w ↦ π ^ (finrank ℝ V / 2 : ℝ) * Real.exp (-π^2 * ‖w‖^2)\n have A : Tendsto (fun (c : ℝ) ↦ ∫ w : V, (c ^ finrank ℝ V * φ (c • (v - w))) • f w)\n atTop (𝓝 (f v)) := by\n apply tendsto_integral_comp_smul_smul_of_integrable'\n · exact fun x ↦ by positivity\n · rw [integral_mul_left, GaussianFourier.integral_rexp_neg_mul_sq_norm (by positivity)]\n nth_rewrite 2 [← pow_one π]\n rw [← rpow_natCast, ← rpow_natCast, ← rpow_sub pi_pos, ← rpow_mul pi_nonneg,\n ← rpow_add pi_pos]\n ring_nf\n exact rpow_zero _\n · have A : Tendsto (fun (w : V) ↦ π^2 * ‖w‖^2) (cobounded V) atTop := by\n rw [tendsto_const_mul_atTop_of_pos (by positivity)]\n apply (tendsto_pow_atTop two_ne_zero).comp tendsto_norm_cobounded_atTop\n have B := tendsto_rpow_mul_exp_neg_mul_atTop_nhds_zero (finrank ℝ V / 2) 1\n zero_lt_one |>.comp A |>.const_mul (π ^ (-finrank ℝ V / 2 : ℝ))\n rw [mul_zero] at B\n convert B using 2 with x\n simp only [neg_mul, one_mul, Function.comp_apply, ← mul_assoc, ← rpow_natCast, φ]\n congr 1\n rw [mul_rpow (by positivity) (by positivity), ← rpow_mul pi_nonneg,\n ← rpow_mul (norm_nonneg _), ← mul_assoc, ← rpow_add pi_pos, mul_comm]\n congr <;> ring\n · exact hf\n · exact h'f\n have B : Tendsto\n (fun (c : ℝ) ↦ ∫ w : V, ((c^(1/2:ℝ)) ^ finrank ℝ V * φ ((c^(1/2:ℝ)) • (v - w))) • f w)\n atTop (𝓝 (f v)) :=\n A.comp (tendsto_rpow_atTop (by norm_num))\n apply B.congr'\n filter_upwards [Ioi_mem_atTop 0] with c (hc : 0 < c)\n congr with w\n rw [← coe_smul]\n congr\n rw [ofReal_mul, ofReal_mul, ofReal_exp, ← mul_assoc]\n congr\n · rw [mul_cpow_ofReal_nonneg pi_nonneg hc.le, ← rpow_natCast, ← rpow_mul hc.le, mul_comm,\n ofReal_cpow pi_nonneg, ofReal_cpow hc.le]\n simp [div_eq_inv_mul]\n · norm_cast\n simp only [one_div, norm_smul, Real.norm_eq_abs, mul_pow, _root_.sq_abs, neg_mul, neg_inj,\n ← rpow_natCast, ← rpow_mul hc.le, mul_assoc]\n norm_num","line":104,"end_line":150,"proof_status":"formalized"} {"id":"lem:threelines","label":"threelines","background_color":"#1CAC78","border_color":"green","kind":"ellipse","dep_graph_url":"https://florisvandoorn.com/BonnAnalysis/blueprint/dep_graph_document.html","dependencies":[],"nlp_text":"Let \\(S\\) be the strip \\(S:=\\{ z \\in \\mathbb {C}\\ | \\ 0 {\\lt} \\mathrm{Re} \\, z {\\lt} 1 \\} \\). Let \\(f: \\overline{S} \\to \\mathbb {C}\\) be a function that is holomorphic on \\(S\\) and continuous and bounded on \\(\\overline{S}\\).Assume \\(M_0, M_1\\) are positive real numbers such that for all values of \\(y\\) in \\(\\mathbb {R}\\), we have \\[ | \\phi (iy) | \\leq M_0 \\ \\qquad | \\phi (1+iy) | \\leq M_1 \\]","doc_url":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/DiffContOnCl.norm_le_pow_mul_pow","latex_link":"chap-interpolation.html#lem:threelines","lean_link":"https://fpvandoorn.github.io/BonnAnalysis/docs/find/#doc/DiffContOnCl.norm_le_pow_mul_pow","lean_decl_name":"DiffContOnCl.norm_le_pow_mul_pow","kind_description":"theorems and lemmas","status_from_color":"formalized","lookup_in_mathlib4v4.22.0":true,"found_in_mathlib4v4.22.0":false,"source_repo":"remote_github","source_path":"https://raw.githubusercontent.com/fpvandoorn/BonnAnalysis/f3acd7b6e64e9949e697d595d495e01dc4c3dbf9/BonnAnalysis/ComplexInterpolation.lean","lean4_code":"theorem DiffContOnCl.norm_le_pow_mul_pow {a b : ℝ} {f : ℂ → ℂ} (hab: a