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| import OAI.Geometry.KahlerSplitting.AreaBounds | |
| namespace OAI | |
| noncomputable section | |
| open scoped Manifold ContDiff | |
| open Set | |
| open Set Topology Filter Metric | |
| open Set Metric Filter Topology | |
| open Set MeasureTheory Metric Filter Topology | |
| open scoped Interval | |
| open Set MeasureTheory | |
| open scoped ENNReal | |
| open Set Metric | |
| namespace UniversalCoverSplitting | |
| theorem exists_brody_maximum {a : ℂ → ℝ} {c : ℂ} {R ε : ℝ} | |
| (hR : 0 < R) (hε : 0 < ε) (ha : ContinuousOn a (closedBall c R)) | |
| (han : ∀ z ∈ closedBall c R, 0 ≤ a z) | |
| (hw : ∃ z ∈ ball c R, ε ≤ (R - dist z c) * a z) : | |
| ∃ p ∈ ball c R, 0 < a p ∧ ε ≤ (R - dist p c) * a p ∧ | |
| ∀ z ∈ ball p ((R - dist p c) / 2), z ∈ ball c R ∧ a z ≤ 2 * a p := by | |
| let w := fun z ↦ (R - dist z c) * a z | |
| have hc : ContinuousOn w (closedBall c R) := | |
| (continuousOn_const.sub (continuous_id.dist continuous_const).continuousOn).mul ha | |
| obtain ⟨p,hp,hmax⟩ := (isCompact_closedBall c R).exists_isMaxOn | |
| (nonempty_closedBall.mpr hR.le) hc | |
| obtain ⟨z,hz,hwz⟩ := hw | |
| have hep : ε ≤ w p := hwz.trans (hmax (ball_subset_closedBall hz)) | |
| have hap := han p hp | |
| have hdp : dist p c < R := by | |
| have hh : dist p c ≤ R := hp | |
| by_contra hn | |
| have he : dist p c = R := le_antisymm hh (le_of_not_gt hn) | |
| dsimp [w] at hep | |
| rw [he, sub_self, zero_mul] at hep | |
| linarith | |
| have hapos : 0 < a p := by | |
| by_contra hn | |
| have he : a p = 0 := le_antisymm (le_of_not_gt hn) hap | |
| dsimp [w] at hep | |
| rw [he, mul_zero] at hep | |
| linarith | |
| refine ⟨p,hdp,hapos,hep,?_⟩ | |
| intro v hv | |
| have hvp : dist v p < (R - dist p c) / 2 := hv | |
| have htri := dist_triangle v p c | |
| have hvd : dist v c < R := by linarith | |
| refine ⟨hvd,?_⟩ | |
| have ham := han v (ball_subset_closedBall hvd) | |
| have hvmax := hmax (ball_subset_closedBall hvd) | |
| dsimp [w] at hvmax | |
| have hdist : (R - dist p c) / 2 ≤ R - dist v c := by linarith | |
| have hm := mul_le_mul_of_nonneg_right hdist ham | |
| have hpdist : 0 < R - dist p c := sub_pos.mpr hdp | |
| nlinarith | |
| theorem exists_brody_rescaling {a : ℂ → ℝ} {c : ℂ} {R ε : ℝ} | |
| (hR : 0 < R) (hε : 0 < ε) (ha : ContinuousOn a (closedBall c R)) | |
| (han : ∀ z ∈ closedBall c R, 0 ≤ a z) | |
| (hw : ∃ z ∈ ball c R, ε ≤ (R - dist z c) * a z) : | |
| ∃ p ∈ ball c R, 0 < a p ∧ a p / a p = 1 ∧ | |
| ∀ ζ ∈ ball (0 : ℂ) (ε/4), | |
| p + ζ / (a p : ℂ) ∈ ball c R ∧ a (p + ζ / (a p : ℂ)) / a p ≤ 2 := by | |
| obtain ⟨p,hp,hap,hep,hbound⟩ := exists_brody_maximum hR hε ha han hw | |
| refine ⟨p,hp,hap,div_self hap.ne',?_⟩ | |
| intro ζ hζ | |
| have hn : ‖ζ‖ < ε/4 := by simpa using hζ | |
| have hd : dist (p + ζ / (a p : ℂ)) p = ‖ζ‖ / a p := by | |
| rw [dist_eq_norm] | |
| simp [Complex.norm_real, abs_of_pos hap] | |
| have hnear : p + ζ / (a p : ℂ) ∈ ball p ((R-dist p c)/2) := by | |
| rw [mem_ball, hd, div_lt_iff₀ hap] | |
| nlinarith | |
| obtain ⟨hmem,hle⟩ := hbound _ hnear | |
| exact ⟨hmem,(div_le_iff₀ hap).mpr hle⟩ | |
| end UniversalCoverSplitting | |
| namespace UniversalCoverSplitting | |
| open Set Metric Filter Topology MeasureTheory | |
| open scoped Manifold ENNReal | |
| variable {n : ℕ} {X : ComplexManifold n} | |
| theorem small_area_weighted_speed [CompactSpace X.Carrier] (g : KahlerMetric X) | |
| {ε : ℝ} (hε : 0 < ε) : | |
| ∃ η : ℝ, 0 < η ∧ ∀ (f : ℂ → X.Carrier) (Ω : Set ℂ), IsOpen Ω → | |
| MDifferentiableOn 𝓘(ℂ, ℂ) (model n) f Ω → | |
| ∀ (c : ℂ) (R : ℝ), 0 < R → closedBall c R ⊆ Ω → | |
| curveArea g f (ball c R) < ENNReal.ofReal η → | |
| ∀ z ∈ ball c R, (R - dist z c) * curveSpeed g f z < ε := by | |
| obtain ⟨η,hη,hlower⟩ := exists_uniform_normalized_curveArea_lowerBound g | |
| (by positivity : 0 < ε/4) | |
| refine ⟨η,hη,?_⟩ | |
| intro f Ω hΩ hf c R hR hsub harea z hz | |
| by_contra hsmall | |
| obtain ⟨p,hp,hap,_,hbr⟩ := exists_brody_rescaling hR hε | |
| ((curveSpeed_continuousOn g hΩ hf).mono hsub) | |
| (fun z _ ↦ curveSpeed_nonneg g f z) ⟨z,hz,le_of_not_gt hsmall⟩ | |
| let a := (curveSpeed g f p)⁻¹ | |
| have ha : 0 < a := inv_pos.mpr hap | |
| let φ : ℂ → ℂ := fun ζ ↦ p + a • ζ | |
| have hφ (ζ : ℂ) : φ ζ = p + ζ / (curveSpeed g f p : ℂ) := by | |
| simp only [φ,a,Complex.real_smul,Complex.ofReal_inv,div_eq_mul_inv,mul_comm] | |
| have hφmem (ζ : ℂ) (hζ : ζ ∈ ball (0 : ℂ) (ε/4)) : φ ζ ∈ ball c R := by | |
| rw [hφ]; exact (hbr ζ hζ).1 | |
| let k : ℂ → X.Carrier := f ∘ φ | |
| have hφdiff (ζ : ℂ) : MDifferentiableAt 𝓘(ℂ, ℂ) 𝓘(ℂ, ℂ) φ ζ := by | |
| apply DifferentiableAt.mdifferentiableAt | |
| simpa only [φ,Complex.real_smul,id_eq] using | |
| (((differentiableAt_id (𝕜 := ℂ) (x := ζ)).const_mul (a : ℂ)).const_add p) | |
| have hkdiff : MDifferentiableOn 𝓘(ℂ, ℂ) (model n) k (ball 0 (ε/4)) := by | |
| intro ζ hζ | |
| exact ((hf.mdifferentiableAt (hΩ.mem_nhds (hsub (ball_subset_closedBall (hφmem ζ hζ))))).comp ζ | |
| (hφdiff ζ)).mdifferentiableWithinAt | |
| have hkSpeed (ζ : ℂ) (hζ : ζ ∈ ball (0 : ℂ) (ε/4)) : | |
| curveSpeed g k ζ = a * curveSpeed g f (φ ζ) := by | |
| simpa only [k,Function.comp_def,φ,Complex.real_smul,Complex.norm_real, | |
| Real.norm_eq_abs,abs_of_pos ha] using | |
| curveSpeed_affine g p (a : ℂ) ζ | |
| (hf.mdifferentiableAt (hΩ.mem_nhds (hsub (ball_subset_closedBall (hφmem ζ hζ))))) | |
| have hk0 : curveSpeed g k 0 = 1 := by | |
| rw [hkSpeed 0 (mem_ball_self (by positivity))] | |
| simp [φ,a,inv_mul_cancel₀ hap.ne'] | |
| have hk2 (ζ : ℂ) (hζ : ζ ∈ ball (0 : ℂ) (ε/4)) : curveSpeed g k ζ ≤ 2 := by | |
| rw [hkSpeed ζ hζ,hφ] | |
| simpa only [a,div_eq_mul_inv,mul_comm] using (hbr ζ hζ).2 | |
| have hsubarea : curveArea g k (ball 0 (ε/4)) ≤ curveArea g f (ball c R) := by | |
| change curveArea g (fun ζ ↦ f (p + a • ζ)) (ball 0 (ε/4)) ≤ _ | |
| rw [curveArea_positive_affine g _ measurableSet_ball p ha] | |
| · exact curveArea_mono g f (by rintro _ ⟨ζ,hζ,rfl⟩; exact hφmem ζ hζ) | |
| · rintro _ ⟨ζ,hζ,rfl⟩ | |
| exact hf.mdifferentiableAt (hΩ.mem_nhds (hsub (ball_subset_closedBall (hφmem ζ hζ)))) | |
| exact (not_lt_of_ge ((hlower k hkdiff hk0 hk2).trans hsubarea)) harea | |
| end UniversalCoverSplitting | |
| namespace UniversalCoverSplitting | |
| open Set Metric Filter Topology MeasureTheory | |
| open scoped Manifold ENNReal | |
| variable {n : ℕ} {X : ComplexManifold n} | |
| theorem exists_small_area_speed_bound [CompactSpace X.Carrier] (g : KahlerMetric X) | |
| {Ω K : Set ℂ} (hΩ : IsOpen Ω) (hK : IsCompact K) (hKΩ : K ⊆ Ω) | |
| {ε : ℝ} (hε : 0 < ε) : | |
| ∃ η : ℝ, 0 < η ∧ ∀ f : ℂ → X.Carrier, | |
| MDifferentiableOn 𝓘(ℂ, ℂ) (model n) f Ω → | |
| curveArea g f Ω < ENNReal.ofReal η → ∀ z ∈ K, curveSpeed g f z < ε := by | |
| obtain ⟨R,hR,hball⟩ := hK.exists_cthickening_subset_open hΩ hKΩ | |
| obtain ⟨η,hη,hb⟩ := small_area_weighted_speed g (mul_pos hε hR) | |
| refine ⟨η,hη,?_⟩ | |
| intro f hf harea z hz | |
| have hc : closedBall z R ⊆ Ω := (closedBall_subset_cthickening hz R).trans hball | |
| have he := hb f Ω hΩ hf z R hR hc ((curveArea_mono g f | |
| (ball_subset_closedBall.trans hc)).trans_lt harea) z (mem_ball_self hR) | |
| simp only [dist_self,sub_zero] at he | |
| nlinarith | |
| theorem small_area_derivatives_tendstoUniformlyOn [CompactSpace X.Carrier] | |
| (g : KahlerMetric X) {Ω : Set ℂ} (hΩ : IsOpen Ω) | |
| (h : ℕ → ℂ → X.Carrier) | |
| (hhol : ∀ j, MDifferentiableOn 𝓘(ℂ, ℂ) (model n) (h j) Ω) | |
| (harea : Tendsto (fun j ↦ curveArea g (h j) Ω) atTop (𝓝 0)) | |
| {K : Set ℂ} (hK : IsCompact K) (hKΩ : K ⊆ Ω) : | |
| TendstoUniformlyOn (fun j z ↦ curveSpeed g (h j) z) (fun _ ↦ 0) atTop K := by | |
| apply Metric.tendstoUniformlyOn_iff.mpr | |
| intro ε hε | |
| obtain ⟨η,hη,hb⟩ := exists_small_area_speed_bound g hΩ hK hKΩ hε | |
| filter_upwards [harea.eventually_lt_const (ENNReal.ofReal_pos.mpr hη)] with j hj | |
| intro z hz | |
| simpa only [Real.dist_eq,zero_sub,abs_neg,abs_of_nonneg (curveSpeed_nonneg g (h j) z)] using | |
| hb (h j) (hhol j) hj z hz | |
| end UniversalCoverSplitting | |
| open Set Metric Filter Topology | |
| open scoped Manifold | |
| namespace UniversalCoverSplitting | |
| variable {n : ℕ} {X : ComplexManifold n} | |
| theorem bounded_curveSpeed_local_trapping (g : KahlerMetric X) (c : X.Carrier) | |
| {V : Set X.Carrier} (hV : V ∈ 𝓝 c) {L : ℝ} (hL : 0 ≤ L) : | |
| ∃ W ∈ 𝓝 c, ∃ r : ℝ, 0 < r ∧ ∀ ρ : ℝ, 0 ≤ ρ → ρ ≤ r → | |
| ∀ (f : ℂ → X.Carrier) (Ω : Set ℂ), | |
| IsOpen Ω → MDifferentiableOn 𝓘(ℂ, ℂ) (model n) f Ω → | |
| closedBall (0 : ℂ) ρ ⊆ Ω → f 0 ∈ W → | |
| (∀ z ∈ closedBall (0 : ℂ) ρ, curveSpeed g f z ≤ L) → | |
| MapsTo f (closedBall (0 : ℂ) ρ) V := by | |
| let e : OpenPartialHomeomorph X.Carrier (Model n) := | |
| { extChartAt (model n) c with | |
| continuousOn_toFun := continuousOn_extChartAt c | |
| continuousOn_invFun := continuousOn_extChartAt_symm c | |
| open_source := isOpen_extChartAt_source c | |
| open_target := isOpen_extChartAt_target c } | |
| have hc : c ∈ e.source := mem_extChartAt_source c | |
| have het : e c ∈ e.target := e.map_source hc | |
| have hnear : e.target ∩ e.symm ⁻¹' V ∈ 𝓝 (e c) := | |
| inter_mem (e.open_target.mem_nhds het) | |
| ((e.continuousOn_symm.continuousAt (e.open_target.mem_nhds het)) | |
| (by simpa only [e.left_inv hc] using hV)) | |
| obtain ⟨R,hR,hRsub⟩ := Metric.nhds_basis_closedBall.mem_iff.mp hnear | |
| have he : closedBall (e c) R ⊆ e.target := fun z hz ↦ (hRsub hz).1 | |
| obtain ⟨C,D,hC,_,hcomp⟩ := g.exists_chart_speed_comparison c | |
| (isCompact_closedBall (e c) R) he | |
| let W := e.source ∩ e ⁻¹' ball (e c) (R/2) | |
| have hW : W ∈ 𝓝 c := (e.isOpen_inter_preimage isOpen_ball).mem_nhds | |
| ⟨hc,by simpa using half_pos hR⟩ | |
| let r := R / (4 * (C * L + 1)) | |
| have hCL : 0 ≤ C * L := mul_nonneg hC.le hL | |
| have hr : 0 < r := div_pos hR (by positivity) | |
| have hrCL : C * L * r ≤ R / 4 := by | |
| dsimp [r] | |
| apply (le_div_iff₀ (by norm_num : (0:ℝ) < 4)).mpr | |
| have hd : 0 < 4 * (C * L + 1) := by positivity | |
| field_simp | |
| nlinarith | |
| refine ⟨W,hW,r,hr,?_⟩ | |
| intro ρ hρ hρr f Ω hΩ hf hsub hzero hspeed z hz | |
| have hρCL : C * L * ρ ≤ R / 4 := | |
| (mul_le_mul_of_nonneg_left hρr hCL).trans hrCL | |
| have htrap : ∀ z ∈ closedBall (0 : ℂ) ρ, | |
| f z ∈ e.source ∧ e (f z) ∈ ball (e c) R := by | |
| apply chart_trapping_on_disk e hR hCL hρ he (hf.continuousOn.mono hsub) | |
| · refine ⟨hzero.1,?_⟩ | |
| have hh : dist (e (f 0)) (e c) < R/2 := hzero.2 | |
| linarith | |
| · intro w hw hk | |
| obtain ⟨v,hv,hvf⟩ := hk | |
| have hs : f w ∈ e.source := hvf ▸ e.map_target (he hv) | |
| have hv' : e (f w) ∈ closedBall (e c) R := by | |
| rw [← hvf,e.right_inv (he hv)]; exact hv | |
| have hfd := hf.mdifferentiableAt (hΩ.mem_nhds (hsub hw)) | |
| have hed : MDifferentiableAt (model n) (model n) e (f w) := | |
| mdifferentiableAt_extChartAt (by simpa only [e,extChartAt_source] using hs) | |
| refine ⟨(hed.comp w hfd).differentiableAt,?_⟩ | |
| rw [← norm_deriv_eq_norm_fderiv] | |
| change ‖deriv ((extChartAt (model n) c) ∘ f) w‖ ≤ C * L | |
| rw [chart_deriv_curve hfd c hs] | |
| exact ((hcomp (f w) hs hv' (mfderiv 𝓘(ℂ, ℂ) (model n) f w (1:ℂ))).1).trans | |
| (mul_le_mul_of_nonneg_left (hspeed w hw) hC.le) | |
| have ht := htrap z hz | |
| have hv := (hRsub (ball_subset_closedBall ht.2)).2 | |
| simpa only [mem_preimage,e.left_inv ht.1] using hv | |
| end UniversalCoverSplitting | |
| open Set Metric Filter Topology | |
| open scoped Manifold | |
| namespace UniversalCoverSplitting | |
| variable {n : ℕ} {X : ComplexManifold n} | |
| noncomputable abbrev compactManifoldMetric (X : ComplexManifold n) | |
| [CompactSpace X.Carrier] : MetricSpace X.Carrier := by | |
| letI : TopologicalSpace.MetrizableSpace X.Carrier := | |
| Manifold.metrizableSpace 𝓘(ℝ, Model n) X.Carrier | |
| exact TopologicalSpace.metrizableSpaceMetric X.Carrier | |
| local instance [CompactSpace X.Carrier] : MetricSpace X.Carrier := compactManifoldMetric X | |
| theorem bounded_curveSpeed_uniform_trapping [CompactSpace X.Carrier] | |
| (g : KahlerMetric X) {L ε : ℝ} (hL : 0 ≤ L) (hε : 0 < ε) : | |
| ∃ r : ℝ, 0 < r ∧ ∀ ρ : ℝ, 0 ≤ ρ → ρ ≤ r → | |
| ∀ (f : ℂ → X.Carrier) (Ω : Set ℂ), | |
| IsOpen Ω → MDifferentiableOn 𝓘(ℂ, ℂ) (model n) f Ω → | |
| closedBall (0 : ℂ) ρ ⊆ Ω → | |
| (∀ z ∈ closedBall (0 : ℂ) ρ, curveSpeed g f z ≤ L) → | |
| ∀ z ∈ closedBall (0 : ℂ) ρ, dist (f 0) (f z) < ε := by | |
| classical | |
| choose W hW r hr hb using fun c : X.Carrier ↦ | |
| bounded_curveSpeed_local_trapping g c (ball_mem_nhds c (half_pos hε)) hL | |
| let V (c : X.Carrier) := W c ∩ ball c (ε/2) | |
| have hV (c : X.Carrier) : V c ∈ 𝓝 c := inter_mem (hW c) (ball_mem_nhds c (half_pos hε)) | |
| obtain ⟨s,hs⟩ := CompactSpace.elim_nhds_subcover V hV | |
| have covered (x : X.Carrier) : ∃ c ∈ s, x ∈ V c := by | |
| have hx : x ∈ ⋃ c ∈ s, V c := by rw [hs]; trivial | |
| simpa only [mem_iUnion,exists_prop] using hx | |
| by_cases hne : s.Nonempty | |
| · refine ⟨s.inf' hne r, (Finset.lt_inf'_iff hne).mpr (fun c _ ↦ hr c),?_⟩ | |
| intro ρ hρ hρr f Ω hΩ hf hsub hspeed z hz | |
| obtain ⟨c,hcs,hc⟩ := covered (f 0) | |
| have ht := hb c ρ hρ (hρr.trans (s.inf'_le r hcs)) f Ω hΩ hf hsub hc.1 hspeed hz | |
| calc | |
| dist (f 0) (f z) ≤ dist (f 0) c + dist c (f z) := dist_triangle _ _ _ | |
| _ < ε/2 + ε/2 := add_lt_add hc.2 (by simpa only [mem_ball,dist_comm] using ht) | |
| _ = ε := by ring | |
| · refine ⟨1,by norm_num,?_⟩ | |
| intro ρ hρ hρr f | |
| obtain ⟨c,hcs,_⟩ := covered (f 0) | |
| exact (hne ⟨c,hcs⟩).elim | |
| theorem bounded_curveSpeed_equicontinuousOn [CompactSpace X.Carrier] | |
| (g : KahlerMetric X) {ι : Type*} (f : ι → ℂ → X.Carrier) | |
| {Ω : Set ℂ} (hΩ : IsOpen Ω) | |
| (hf : ∀ i, MDifferentiableOn 𝓘(ℂ, ℂ) (model n) (f i) Ω) | |
| (hb : ∀ p ∈ Ω, ∃ R L : ℝ, 0 < R ∧ 0 ≤ L ∧ closedBall p R ⊆ Ω ∧ | |
| ∀ i z, z ∈ closedBall p R → curveSpeed g (f i) z ≤ L) : | |
| EquicontinuousOn f Ω := by | |
| intro p hp | |
| apply EquicontinuousAt.equicontinuousWithinAt | |
| rw [Metric.equicontinuousAt_iff] | |
| intro ε hε | |
| obtain ⟨R,L,hR,hL,hRΩ,hbound⟩ := hb p hp | |
| obtain ⟨r,hr,htrap⟩ := bounded_curveSpeed_uniform_trapping g hL hε | |
| let ρ := min r R | |
| have hρ : 0 < ρ := lt_min hr hR | |
| refine ⟨ρ,hρ,?_⟩ | |
| intro z hz i | |
| let φ : ℂ → ℂ := fun w ↦ p + w | |
| have hφdiff : MDifferentiable 𝓘(ℂ, ℂ) 𝓘(ℂ, ℂ) φ := | |
| (differentiable_id.const_add p).mdifferentiable | |
| have hφmem {w : ℂ} (hw : w ∈ closedBall (0 : ℂ) ρ) : φ w ∈ closedBall p R := by | |
| simpa [φ,mem_closedBall,dist_eq_norm] using | |
| (hw.trans (min_le_right r R)) | |
| have hk : MDifferentiableOn 𝓘(ℂ, ℂ) (model n) (f i ∘ φ) (φ ⁻¹' Ω) := | |
| (hf i).comp hφdiff.mdifferentiableOn (fun _ hw ↦ hw) | |
| have hspeed (w : ℂ) (hw : w ∈ closedBall (0 : ℂ) ρ) : | |
| curveSpeed g (f i ∘ φ) w ≤ L := by | |
| have ha := curveSpeed_affine g p (1:ℂ) w | |
| (by simpa only [one_mul,φ] using | |
| (hf i).mdifferentiableAt (hΩ.mem_nhds (hRΩ (hφmem hw)))) | |
| have hs : curveSpeed g (f i ∘ φ) w = curveSpeed g (f i) (φ w) := by | |
| simpa only [φ,Function.comp_def,one_mul,norm_one] using ha | |
| exact hs.trans_le (hbound i (φ w) (hφmem hw)) | |
| have hw : z-p ∈ closedBall (0 : ℂ) ρ := by | |
| simpa only [mem_closedBall,dist_zero_right,← dist_eq_norm] using hz.le | |
| have ht := htrap ρ hρ.le (min_le_left r R) (f i ∘ φ) (φ ⁻¹' Ω) | |
| (hΩ.preimage hφdiff.continuous) hk (fun w hw ↦ hRΩ (hφmem hw)) hspeed (z-p) hw | |
| simpa only [Function.comp_def,φ,add_zero,add_sub_cancel] using ht | |
| end UniversalCoverSplitting | |
| open Set Filter Topology | |
| namespace UniversalCoverSplitting | |
| theorem equicontinuous_compact_target_subsequence | |
| {T Y : Type*} [TopologicalSpace T] [LocallyCompactSpace T] | |
| [SecondCountableTopology T] [MetricSpace Y] [CompactSpace Y] | |
| (f : ℕ → C(T,Y)) (he : Equicontinuous (fun j x ↦ f j x)) : | |
| ∃ σ : ℕ → ℕ, StrictMono σ ∧ ∃ g : C(T,Y), | |
| Tendsto (f ∘ σ) atTop (𝓝 g) := by | |
| classical | |
| have he' : Equicontinuous (fun (i : range f) x ↦ i.val x) := by | |
| choose a ha using fun i : range f ↦ i.property | |
| have hh := he.comp a | |
| simpa only [Function.comp_def,ha] using hh | |
| have : T2Space (UniformOnFun T Y {K : Set T | IsCompact K}) := | |
| UniformOnFun.t2Space_of_covering (by | |
| ext x | |
| simp only [mem_sUnion, mem_ofPred_eq, mem_univ, iff_true] | |
| exact ⟨{x},isCompact_singleton,mem_singleton x⟩) | |
| have hc : IsCompact (closure (range f)) := by | |
| apply ArzelaAscoli.isCompact_closure_of_isClosedEmbedding | |
| (F := fun (h : C(T,Y)) x ↦ h x) (𝔖 := {K : Set T | IsCompact K}) | |
| (fun _ h ↦ h) | |
| ContinuousMap.isUniformEmbedding_toUniformOnFunIsCompact.isClosedEmbedding | |
| · exact fun K _ ↦ he'.equicontinuousOn K | |
| · exact fun _ _ _ _ ↦ ⟨univ,isCompact_univ,fun _ _ ↦ mem_univ _⟩ | |
| obtain ⟨g,_,σ,hσ,hg⟩ := hc.tendsto_subseq (fun j ↦ subset_closure (mem_range_self j)) | |
| exact ⟨σ,hσ,g,hg⟩ | |
| end UniversalCoverSplitting | |
| end | |
| end OAI | |