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protected TendstoUniformly.continuous (h : TendstoUniformly F f p) (hc : ∀ᶠ n in p, Continuous (F n)) [NeBot p] : Continuous f := h.tendstoLocallyUniformly.continuous hc /-!
theorem
Topology
[ "Mathlib.Topology.UniformSpace.LocallyUniformConvergence" ]
Mathlib/Topology/UniformSpace/UniformApproximation.lean
TendstoUniformly.continuous
A uniform limit of continuous functions is continuous.
tendsto_comp_of_locally_uniform_limit_within (h : ContinuousWithinAt f s x) (hg : Tendsto g p (𝓝[s] x)) (hunif : ∀ u ∈ 𝓤 β, ∃ t ∈ 𝓝[s] x, ∀ᶠ n in p, ∀ y ∈ t, (f y, F n y) ∈ u) : Tendsto (fun n => F n (g n)) p (𝓝 (f x)) := by refine Uniform.tendsto_nhds_right.2 fun u₀ hu₀ => ?_ obtain ⟨u₁, h₁, u₁₀⟩ : ∃ u ∈ 𝓤 β, u ○ u ⊆ u₀ := comp_mem_uniformity_sets hu₀ rcases hunif u₁ h₁ with ⟨s, sx, hs⟩ have A : ∀ᶠ n in p, g n ∈ s := hg sx have B : ∀ᶠ n in p, (f x, f (g n)) ∈ u₁ := hg (Uniform.continuousWithinAt_iff'_right.1 h h₁) exact B.mp <| A.mp <| hs.mono fun y H1 H2 H3 => u₁₀ (prodMk_mem_compRel H3 (H1 _ H2))
theorem
Topology
[ "Mathlib.Topology.UniformSpace.LocallyUniformConvergence" ]
Mathlib/Topology/UniformSpace/UniformApproximation.lean
tendsto_comp_of_locally_uniform_limit_within
If `Fₙ` converges locally uniformly on a neighborhood of `x` within a set `s` to a function `f` which is continuous at `x` within `s`, and `gₙ` tends to `x` within `s`, then `Fₙ (gₙ)` tends to `f x`.
tendsto_comp_of_locally_uniform_limit (h : ContinuousAt f x) (hg : Tendsto g p (𝓝 x)) (hunif : ∀ u ∈ 𝓤 β, ∃ t ∈ 𝓝 x, ∀ᶠ n in p, ∀ y ∈ t, (f y, F n y) ∈ u) : Tendsto (fun n => F n (g n)) p (𝓝 (f x)) := by rw [← continuousWithinAt_univ] at h rw [← nhdsWithin_univ] at hunif hg exact tendsto_comp_of_locally_uniform_limit_within h hg hunif
theorem
Topology
[ "Mathlib.Topology.UniformSpace.LocallyUniformConvergence" ]
Mathlib/Topology/UniformSpace/UniformApproximation.lean
tendsto_comp_of_locally_uniform_limit
If `Fₙ` converges locally uniformly on a neighborhood of `x` to a function `f` which is continuous at `x`, and `gₙ` tends to `x`, then `Fₙ (gₙ)` tends to `f x`.
TendstoLocallyUniformlyOn.tendsto_comp (h : TendstoLocallyUniformlyOn F f p s) (hf : ContinuousWithinAt f s x) (hx : x ∈ s) (hg : Tendsto g p (𝓝[s] x)) : Tendsto (fun n => F n (g n)) p (𝓝 (f x)) := tendsto_comp_of_locally_uniform_limit_within hf hg fun u hu => h u hu x hx
theorem
Topology
[ "Mathlib.Topology.UniformSpace.LocallyUniformConvergence" ]
Mathlib/Topology/UniformSpace/UniformApproximation.lean
TendstoLocallyUniformlyOn.tendsto_comp
If `Fₙ` tends locally uniformly to `f` on a set `s`, and `gₙ` tends to `x` within `s`, then `Fₙ gₙ` tends to `f x` if `f` is continuous at `x` within `s` and `x ∈ s`.
TendstoUniformlyOn.tendsto_comp (h : TendstoUniformlyOn F f p s) (hf : ContinuousWithinAt f s x) (hg : Tendsto g p (𝓝[s] x)) : Tendsto (fun n => F n (g n)) p (𝓝 (f x)) := tendsto_comp_of_locally_uniform_limit_within hf hg fun u hu => ⟨s, self_mem_nhdsWithin, h u hu⟩
theorem
Topology
[ "Mathlib.Topology.UniformSpace.LocallyUniformConvergence" ]
Mathlib/Topology/UniformSpace/UniformApproximation.lean
TendstoUniformlyOn.tendsto_comp
If `Fₙ` tends uniformly to `f` on a set `s`, and `gₙ` tends to `x` within `s`, then `Fₙ gₙ` tends to `f x` if `f` is continuous at `x` within `s`.
TendstoLocallyUniformly.tendsto_comp (h : TendstoLocallyUniformly F f p) (hf : ContinuousAt f x) (hg : Tendsto g p (𝓝 x)) : Tendsto (fun n => F n (g n)) p (𝓝 (f x)) := tendsto_comp_of_locally_uniform_limit hf hg fun u hu => h u hu x
theorem
Topology
[ "Mathlib.Topology.UniformSpace.LocallyUniformConvergence" ]
Mathlib/Topology/UniformSpace/UniformApproximation.lean
TendstoLocallyUniformly.tendsto_comp
If `Fₙ` tends locally uniformly to `f`, and `gₙ` tends to `x`, then `Fₙ gₙ` tends to `f x`.
TendstoUniformly.tendsto_comp (h : TendstoUniformly F f p) (hf : ContinuousAt f x) (hg : Tendsto g p (𝓝 x)) : Tendsto (fun n => F n (g n)) p (𝓝 (f x)) := h.tendstoLocallyUniformly.tendsto_comp hf hg
theorem
Topology
[ "Mathlib.Topology.UniformSpace.LocallyUniformConvergence" ]
Mathlib/Topology/UniformSpace/UniformApproximation.lean
TendstoUniformly.tendsto_comp
If `Fₙ` tends uniformly to `f`, and `gₙ` tends to `x`, then `Fₙ gₙ` tends to `f x`.
TendstoUniformlyOnFilter (F : ι → α → β) (f : α → β) (p : Filter ι) (p' : Filter α) := ∀ u ∈ 𝓤 β, ∀ᶠ n : ι × α in p ×ˢ p', (f n.snd, F n.fst n.snd) ∈ u
def
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter
A sequence of functions `Fₙ` converges uniformly on a filter `p'` to a limiting function `f` with respect to the filter `p` if, for any entourage of the diagonal `u`, one has `p ×ˢ p'`-eventually `(f x, Fₙ x) ∈ u`.
tendstoUniformlyOnFilter_iff_tendsto : TendstoUniformlyOnFilter F f p p' ↔ Tendsto (fun q : ι × α => (f q.2, F q.1 q.2)) (p ×ˢ p') (𝓤 β) := Iff.rfl
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOnFilter_iff_tendsto
A sequence of functions `Fₙ` converges uniformly on a filter `p'` to a limiting function `f` w.r.t. filter `p` iff the function `(n, x) ↦ (f x, Fₙ x)` converges along `p ×ˢ p'` to the uniformity. In other words: one knows nothing about the behavior of `x` in this limit besides it being in `p'`.
TendstoUniformlyOn (F : ι → α → β) (f : α → β) (p : Filter ι) (s : Set α) := ∀ u ∈ 𝓤 β, ∀ᶠ n in p, ∀ x : α, x ∈ s → (f x, F n x) ∈ u
def
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn
A sequence of functions `Fₙ` converges uniformly on a set `s` to a limiting function `f` with respect to the filter `p` if, for any entourage of the diagonal `u`, one has `p`-eventually `(f x, Fₙ x) ∈ u` for all `x ∈ s`.
tendstoUniformlyOn_iff_tendstoUniformlyOnFilter : TendstoUniformlyOn F f p s ↔ TendstoUniformlyOnFilter F f p (𝓟 s) := by simp only [TendstoUniformlyOn, TendstoUniformlyOnFilter] apply forall₂_congr simp_rw [eventually_prod_principal_iff] simp alias ⟨TendstoUniformlyOn.tendstoUniformlyOnFilter, TendstoUniformlyOnFilter.tendstoUniformlyOn⟩ := tendstoUniformlyOn_iff_tendstoUniformlyOnFilter
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_iff_tendstoUniformlyOnFilter
null
tendstoUniformlyOn_iff_tendsto : TendstoUniformlyOn F f p s ↔ Tendsto (fun q : ι × α => (f q.2, F q.1 q.2)) (p ×ˢ 𝓟 s) (𝓤 β) := by simp [tendstoUniformlyOn_iff_tendstoUniformlyOnFilter, tendstoUniformlyOnFilter_iff_tendsto]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_iff_tendsto
A sequence of functions `Fₙ` converges uniformly on a set `s` to a limiting function `f` w.r.t. filter `p` iff the function `(n, x) ↦ (f x, Fₙ x)` converges along `p ×ˢ 𝓟 s` to the uniformity. In other words: one knows nothing about the behavior of `x` in this limit besides it being in `s`.
TendstoUniformly (F : ι → α → β) (f : α → β) (p : Filter ι) := ∀ u ∈ 𝓤 β, ∀ᶠ n in p, ∀ x : α, (f x, F n x) ∈ u
def
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformly
A sequence of functions `Fₙ` converges uniformly to a limiting function `f` with respect to a filter `p` if, for any entourage of the diagonal `u`, one has `p`-eventually `(f x, Fₙ x) ∈ u` for all `x`.
tendstoUniformlyOn_univ : TendstoUniformlyOn F f p univ ↔ TendstoUniformly F f p := by simp [TendstoUniformlyOn, TendstoUniformly]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_univ
null
tendstoUniformly_iff_tendstoUniformlyOnFilter : TendstoUniformly F f p ↔ TendstoUniformlyOnFilter F f p ⊤ := by rw [← tendstoUniformlyOn_univ, tendstoUniformlyOn_iff_tendstoUniformlyOnFilter, principal_univ]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformly_iff_tendstoUniformlyOnFilter
null
TendstoUniformly.tendstoUniformlyOnFilter (h : TendstoUniformly F f p) : TendstoUniformlyOnFilter F f p ⊤ := by rwa [← tendstoUniformly_iff_tendstoUniformlyOnFilter]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformly.tendstoUniformlyOnFilter
null
tendstoUniformlyOn_iff_tendstoUniformly_comp_coe : TendstoUniformlyOn F f p s ↔ TendstoUniformly (fun i (x : s) => F i x) (f ∘ (↑)) p := forall₂_congr fun u _ => by simp
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_iff_tendstoUniformly_comp_coe
null
tendstoUniformlyOn_iff_restrict {K : Set α} : TendstoUniformlyOn F f p K ↔ TendstoUniformly (fun n : ι => K.restrict (F n)) (K.restrict f) p := tendstoUniformlyOn_iff_tendstoUniformly_comp_coe
lemma
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_iff_restrict
null
tendstoUniformly_iff_tendsto : TendstoUniformly F f p ↔ Tendsto (fun q : ι × α => (f q.2, F q.1 q.2)) (p ×ˢ ⊤) (𝓤 β) := by simp [tendstoUniformly_iff_tendstoUniformlyOnFilter, tendstoUniformlyOnFilter_iff_tendsto]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformly_iff_tendsto
A sequence of functions `Fₙ` converges uniformly to a limiting function `f` w.r.t. filter `p` iff the function `(n, x) ↦ (f x, Fₙ x)` converges along `p ×ˢ ⊤` to the uniformity. In other words: one knows nothing about the behavior of `x` in this limit.
TendstoUniformlyOnFilter.tendsto_at (h : TendstoUniformlyOnFilter F f p p') (hx : 𝓟 {x} ≤ p') : Tendsto (fun n => F n x) p <| 𝓝 (f x) := by refine Uniform.tendsto_nhds_right.mpr fun u hu => mem_map.mpr ?_ filter_upwards [(h u hu).curry] intro i h simpa using h.filter_mono hx
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.tendsto_at
Uniform convergence implies pointwise convergence.
TendstoUniformlyOn.tendsto_at (h : TendstoUniformlyOn F f p s) (hx : x ∈ s) : Tendsto (fun n => F n x) p <| 𝓝 (f x) := h.tendstoUniformlyOnFilter.tendsto_at (le_principal_iff.mpr <| mem_principal.mpr <| singleton_subset_iff.mpr <| hx)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.tendsto_at
Uniform convergence implies pointwise convergence.
TendstoUniformly.tendsto_at (h : TendstoUniformly F f p) (x : α) : Tendsto (fun n => F n x) p <| 𝓝 (f x) := h.tendstoUniformlyOnFilter.tendsto_at le_top
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformly.tendsto_at
Uniform convergence implies pointwise convergence.
TendstoUniformlyOnFilter.mono_left {p'' : Filter ι} (h : TendstoUniformlyOnFilter F f p p') (hp : p'' ≤ p) : TendstoUniformlyOnFilter F f p'' p' := fun u hu => (h u hu).filter_mono (p'.prod_mono_left hp)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.mono_left
null
TendstoUniformlyOnFilter.mono_right {p'' : Filter α} (h : TendstoUniformlyOnFilter F f p p') (hp : p'' ≤ p') : TendstoUniformlyOnFilter F f p p'' := fun u hu => (h u hu).filter_mono (p.prod_mono_right hp)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.mono_right
null
TendstoUniformlyOn.mono (h : TendstoUniformlyOn F f p s) (h' : s' ⊆ s) : TendstoUniformlyOn F f p s' := tendstoUniformlyOn_iff_tendstoUniformlyOnFilter.mpr (h.tendstoUniformlyOnFilter.mono_right (le_principal_iff.mpr <| mem_principal.mpr h'))
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.mono
null
TendstoUniformlyOnFilter.congr {F' : ι → α → β} (hf : TendstoUniformlyOnFilter F f p p') (hff' : ∀ᶠ n : ι × α in p ×ˢ p', F n.fst n.snd = F' n.fst n.snd) : TendstoUniformlyOnFilter F' f p p' := by refine fun u hu => ((hf u hu).and hff').mono fun n h => ?_ rw [← h.right] exact h.left
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.congr
null
TendstoUniformlyOn.congr {F' : ι → α → β} (hf : TendstoUniformlyOn F f p s) (hff' : ∀ᶠ n in p, Set.EqOn (F n) (F' n) s) : TendstoUniformlyOn F' f p s := by rw [tendstoUniformlyOn_iff_tendstoUniformlyOnFilter] at hf ⊢ refine hf.congr ?_ rw [eventually_iff] at hff' ⊢ simp only [Set.EqOn] at hff' simp only [mem_prod_principal, hff', mem_setOf_eq]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.congr
null
tendstoUniformly_congr {F' : ι → α → β} (hF : F =ᶠ[p] F') : TendstoUniformly F f p ↔ TendstoUniformly F' f p := by simp_rw [← tendstoUniformlyOn_univ] at * have HF := EventuallyEq.exists_mem hF exact ⟨fun h => h.congr (by aesop), fun h => h.congr (by simp_rw [eqOn_comm]; aesop)⟩
lemma
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformly_congr
null
TendstoUniformlyOn.congr_right {g : α → β} (hf : TendstoUniformlyOn F f p s) (hfg : EqOn f g s) : TendstoUniformlyOn F g p s := fun u hu => by filter_upwards [hf u hu] with i hi a ha using hfg ha ▸ hi a ha
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.congr_right
null
protected TendstoUniformly.tendstoUniformlyOn (h : TendstoUniformly F f p) : TendstoUniformlyOn F f p s := (tendstoUniformlyOn_univ.2 h).mono (subset_univ s)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformly.tendstoUniformlyOn
null
TendstoUniformlyOnFilter.comp (h : TendstoUniformlyOnFilter F f p p') (g : γ → α) : TendstoUniformlyOnFilter (fun n => F n ∘ g) (f ∘ g) p (p'.comap g) := by rw [tendstoUniformlyOnFilter_iff_tendsto] at h ⊢ exact h.comp (tendsto_id.prodMap tendsto_comap)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.comp
Composing on the right by a function preserves uniform convergence on a filter
TendstoUniformlyOn.comp (h : TendstoUniformlyOn F f p s) (g : γ → α) : TendstoUniformlyOn (fun n => F n ∘ g) (f ∘ g) p (g ⁻¹' s) := by rw [tendstoUniformlyOn_iff_tendstoUniformlyOnFilter] at h ⊢ simpa [TendstoUniformlyOn, comap_principal] using TendstoUniformlyOnFilter.comp h g
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.comp
Composing on the right by a function preserves uniform convergence on a set
TendstoUniformly.comp (h : TendstoUniformly F f p) (g : γ → α) : TendstoUniformly (fun n => F n ∘ g) (f ∘ g) p := by rw [tendstoUniformly_iff_tendstoUniformlyOnFilter] at h ⊢ simpa [principal_univ, comap_principal] using h.comp g
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformly.comp
Composing on the right by a function preserves uniform convergence
UniformContinuous.comp_tendstoUniformlyOnFilter [UniformSpace γ] {g : β → γ} (hg : UniformContinuous g) (h : TendstoUniformlyOnFilter F f p p') : TendstoUniformlyOnFilter (fun i => g ∘ F i) (g ∘ f) p p' := fun _u hu => h _ (hg hu)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformContinuous.comp_tendstoUniformlyOnFilter
Composing on the left by a uniformly continuous function preserves uniform convergence on a filter
UniformContinuous.comp_tendstoUniformlyOn [UniformSpace γ] {g : β → γ} (hg : UniformContinuous g) (h : TendstoUniformlyOn F f p s) : TendstoUniformlyOn (fun i => g ∘ F i) (g ∘ f) p s := fun _u hu => h _ (hg hu)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformContinuous.comp_tendstoUniformlyOn
Composing on the left by a uniformly continuous function preserves uniform convergence on a set
UniformContinuous.comp_tendstoUniformly [UniformSpace γ] {g : β → γ} (hg : UniformContinuous g) (h : TendstoUniformly F f p) : TendstoUniformly (fun i => g ∘ F i) (g ∘ f) p := fun _u hu => h _ (hg hu)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformContinuous.comp_tendstoUniformly
Composing on the left by a uniformly continuous function preserves uniform convergence
TendstoUniformlyOnFilter.prodMap {ι' α' β' : Type*} [UniformSpace β'] {F' : ι' → α' → β'} {f' : α' → β'} {q : Filter ι'} {q' : Filter α'} (h : TendstoUniformlyOnFilter F f p p') (h' : TendstoUniformlyOnFilter F' f' q q') : TendstoUniformlyOnFilter (fun i : ι × ι' => Prod.map (F i.1) (F' i.2)) (Prod.map f f') (p ×ˢ q) (p' ×ˢ q') := by rw [tendstoUniformlyOnFilter_iff_tendsto] at h h' ⊢ rw [uniformity_prod_eq_comap_prod, tendsto_comap_iff, ← map_swap4_prod, tendsto_map'_iff] simpa using h.prodMap h' @[deprecated (since := "2025-03-10")] alias TendstoUniformlyOnFilter.prod_map := TendstoUniformlyOnFilter.prodMap
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.prodMap
null
TendstoUniformlyOn.prodMap {ι' α' β' : Type*} [UniformSpace β'] {F' : ι' → α' → β'} {f' : α' → β'} {p' : Filter ι'} {s' : Set α'} (h : TendstoUniformlyOn F f p s) (h' : TendstoUniformlyOn F' f' p' s') : TendstoUniformlyOn (fun i : ι × ι' => Prod.map (F i.1) (F' i.2)) (Prod.map f f') (p ×ˢ p') (s ×ˢ s') := by rw [tendstoUniformlyOn_iff_tendstoUniformlyOnFilter] at h h' ⊢ simpa only [prod_principal_principal] using h.prodMap h' @[deprecated (since := "2025-03-10")] alias TendstoUniformlyOn.prod_map := TendstoUniformlyOn.prodMap
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.prodMap
null
TendstoUniformly.prodMap {ι' α' β' : Type*} [UniformSpace β'] {F' : ι' → α' → β'} {f' : α' → β'} {p' : Filter ι'} (h : TendstoUniformly F f p) (h' : TendstoUniformly F' f' p') : TendstoUniformly (fun i : ι × ι' => Prod.map (F i.1) (F' i.2)) (Prod.map f f') (p ×ˢ p') := by rw [← tendstoUniformlyOn_univ, ← univ_prod_univ] at * exact h.prodMap h' @[deprecated (since := "2025-03-10")] alias TendstoUniformly.prod_map := TendstoUniformly.prodMap
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformly.prodMap
null
TendstoUniformlyOnFilter.prodMk {ι' β' : Type*} [UniformSpace β'] {F' : ι' → α → β'} {f' : α → β'} {q : Filter ι'} (h : TendstoUniformlyOnFilter F f p p') (h' : TendstoUniformlyOnFilter F' f' q p') : TendstoUniformlyOnFilter (fun (i : ι × ι') a => (F i.1 a, F' i.2 a)) (fun a => (f a, f' a)) (p ×ˢ q) p' := fun u hu => ((h.prodMap h') u hu).diag_of_prod_right @[deprecated (since := "2025-03-10")] alias TendstoUniformlyOnFilter.prod := TendstoUniformlyOnFilter.prodMk
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.prodMk
null
protected TendstoUniformlyOn.prodMk {ι' β' : Type*} [UniformSpace β'] {F' : ι' → α → β'} {f' : α → β'} {p' : Filter ι'} (h : TendstoUniformlyOn F f p s) (h' : TendstoUniformlyOn F' f' p' s) : TendstoUniformlyOn (fun (i : ι × ι') a => (F i.1 a, F' i.2 a)) (fun a => (f a, f' a)) (p ×ˢ p') s := (congr_arg _ s.inter_self).mp ((h.prodMap h').comp fun a => (a, a)) @[deprecated (since := "2025-03-10")] alias TendstoUniformlyOn.prod := TendstoUniformlyOn.prodMk
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.prodMk
null
TendstoUniformly.prodMk {ι' β' : Type*} [UniformSpace β'] {F' : ι' → α → β'} {f' : α → β'} {p' : Filter ι'} (h : TendstoUniformly F f p) (h' : TendstoUniformly F' f' p') : TendstoUniformly (fun (i : ι × ι') a => (F i.1 a, F' i.2 a)) (fun a => (f a, f' a)) (p ×ˢ p') := (h.prodMap h').comp fun a => (a, a) @[deprecated (since := "2025-03-10")] alias TendstoUniformly.prod := TendstoUniformly.prodMk
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformly.prodMk
null
tendsto_prod_filter_iff {c : β} : Tendsto ↿F (p ×ˢ p') (𝓝 c) ↔ TendstoUniformlyOnFilter F (fun _ => c) p p' := by simp_rw [nhds_eq_comap_uniformity, tendsto_comap_iff] rfl
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendsto_prod_filter_iff
Uniform convergence on a filter `p'` to a constant function is equivalent to convergence in `p ×ˢ p'`.
tendsto_prod_principal_iff {c : β} : Tendsto ↿F (p ×ˢ 𝓟 s) (𝓝 c) ↔ TendstoUniformlyOn F (fun _ => c) p s := by rw [tendstoUniformlyOn_iff_tendstoUniformlyOnFilter] exact tendsto_prod_filter_iff
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendsto_prod_principal_iff
Uniform convergence on a set `s` to a constant function is equivalent to convergence in `p ×ˢ 𝓟 s`.
tendsto_prod_top_iff {c : β} : Tendsto ↿F (p ×ˢ ⊤) (𝓝 c) ↔ TendstoUniformly F (fun _ => c) p := by rw [tendstoUniformly_iff_tendstoUniformlyOnFilter] exact tendsto_prod_filter_iff
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendsto_prod_top_iff
Uniform convergence to a constant function is equivalent to convergence in `p ×ˢ ⊤`.
tendstoUniformlyOn_empty : TendstoUniformlyOn F f p ∅ := fun u _ => by simp
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_empty
Uniform convergence on the empty set is vacuously true
tendstoUniformlyOn_singleton_iff_tendsto : TendstoUniformlyOn F f p {x} ↔ Tendsto (fun n : ι => F n x) p (𝓝 (f x)) := by simp_rw [tendstoUniformlyOn_iff_tendsto, Uniform.tendsto_nhds_right, tendsto_def] exact forall₂_congr fun u _ => by simp [preimage]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_singleton_iff_tendsto
Uniform convergence on a singleton is equivalent to regular convergence
Filter.Tendsto.tendstoUniformlyOnFilter_const {g : ι → β} {b : β} (hg : Tendsto g p (𝓝 b)) (p' : Filter α) : TendstoUniformlyOnFilter (fun n : ι => fun _ : α => g n) (fun _ : α => b) p p' := by simpa only [nhds_eq_comap_uniformity, tendsto_comap_iff] using hg.comp (tendsto_fst (g := p'))
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
Filter.Tendsto.tendstoUniformlyOnFilter_const
If a sequence `g` converges to some `b`, then the sequence of constant functions `fun n ↦ fun a ↦ g n` converges to the constant function `fun a ↦ b` on any set `s`
Filter.Tendsto.tendstoUniformlyOn_const {g : ι → β} {b : β} (hg : Tendsto g p (𝓝 b)) (s : Set α) : TendstoUniformlyOn (fun n : ι => fun _ : α => g n) (fun _ : α => b) p s := tendstoUniformlyOn_iff_tendstoUniformlyOnFilter.mpr (hg.tendstoUniformlyOnFilter_const (𝓟 s))
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
Filter.Tendsto.tendstoUniformlyOn_const
If a sequence `g` converges to some `b`, then the sequence of constant functions `fun n ↦ fun a ↦ g n` converges to the constant function `fun a ↦ b` on any set `s`
UniformContinuousOn.tendstoUniformlyOn [UniformSpace α] [UniformSpace γ] {U : Set α} {V : Set β} {F : α → β → γ} (hF : UniformContinuousOn ↿F (U ×ˢ V)) (hU : x ∈ U) : TendstoUniformlyOn F (F x) (𝓝[U] x) V := by set φ := fun q : α × β => ((x, q.2), q) rw [tendstoUniformlyOn_iff_tendsto] change Tendsto (Prod.map ↿F ↿F ∘ φ) (𝓝[U] x ×ˢ 𝓟 V) (𝓤 γ) simp only [nhdsWithin, Filter.prod_eq_inf, comap_inf, inf_assoc, comap_principal, inf_principal] refine hF.comp (Tendsto.inf ?_ <| tendsto_principal_principal.2 fun x hx => ⟨⟨hU, hx.2⟩, hx⟩) simp only [uniformity_prod_eq_comap_prod, tendsto_comap_iff, nhds_eq_comap_uniformity, comap_comap] exact tendsto_comap.prodMk (tendsto_diag_uniformity _ _)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformContinuousOn.tendstoUniformlyOn
null
UniformContinuousOn.tendstoUniformly [UniformSpace α] [UniformSpace γ] {U : Set α} (hU : U ∈ 𝓝 x) {F : α → β → γ} (hF : UniformContinuousOn ↿F (U ×ˢ (univ : Set β))) : TendstoUniformly F (F x) (𝓝 x) := by simpa only [tendstoUniformlyOn_univ, nhdsWithin_eq_nhds.2 hU] using hF.tendstoUniformlyOn (mem_of_mem_nhds hU)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformContinuousOn.tendstoUniformly
null
UniformContinuous₂.tendstoUniformly [UniformSpace α] [UniformSpace γ] {f : α → β → γ} (h : UniformContinuous₂ f) : TendstoUniformly f (f x) (𝓝 x) := UniformContinuousOn.tendstoUniformly univ_mem <| by rwa [univ_prod_univ, uniformContinuousOn_univ]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformContinuous₂.tendstoUniformly
null
tendstoUniformlyOnFilter_iff_of_uniformity {F : X → α → β} {f : α → β} {l : Filter X} {l' : Filter α} {pβ : ιβ → Prop} {sβ : ιβ → Set (β × β)} (hβ : (uniformity β).HasBasis pβ sβ) : TendstoUniformlyOnFilter F f l l' ↔ (∀ i, pβ i → ∀ᶠ n in l ×ˢ l', (f n.2, F n.1 n.2) ∈ sβ i) := by rw [tendstoUniformlyOnFilter_iff_tendsto, hβ.tendsto_right_iff]
lemma
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOnFilter_iff_of_uniformity
An analogue of `Filter.HasBasis.tendsto_right_iff` for `TendstoUniformlyOnFilter`.
tendstoUniformlyOnFilter_iff {F : X → α → β} {f : α → β} {l : Filter X} {l' : Filter α} {pX : ιX → Prop} {sX : ιX → Set X} {pα : ια → Prop} {sα : ια → Set α} {pβ : ιβ → Prop} {sβ : ιβ → Set (β × β)} (hl : l.HasBasis pX sX) (hl' : l'.HasBasis pα sα) (hβ : (uniformity β).HasBasis pβ sβ) : TendstoUniformlyOnFilter F f l l' ↔ (∀ i, pβ i → ∃ j k, (pX j ∧ pα k) ∧ ∀ x a, x ∈ sX j → a ∈ sα k → (f a, F x a) ∈ sβ i) := by simp [hβ.tendstoUniformlyOnFilter_iff_of_uniformity, (hl.prod hl').eventually_iff]
lemma
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOnFilter_iff
An analogue of `Filter.HasBasis.tendsto_iff` for `TendstoUniformlyOnFilter`.
tendstoUniformlyOn_iff_of_uniformity {F : X → α → β} {f : α → β} {l : Filter X} {s : Set α} {pβ : ιβ → Prop} {sβ : ιβ → Set (β × β)} (hβ : (uniformity β).HasBasis pβ sβ) : TendstoUniformlyOn F f l s ↔ (∀ i, pβ i → ∀ᶠ n in l, ∀ x ∈ s, (f x, F n x) ∈ sβ i) := by simp_rw [tendstoUniformlyOn_iff_tendsto, hβ.tendsto_right_iff, eventually_prod_principal_iff]
lemma
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_iff_of_uniformity
An analogue of `Filter.HasBasis.tendsto_right_iff` for `TendstoUniformlyOn`.
tendstoUniformlyOn_iff {F : X → α → β} {f : α → β} {l : Filter X} {s : Set α} {pX : ιX → Prop} {sX : ιX → Set X} {pβ : ιβ → Prop} {sβ : ιβ → Set (β × β)} (hl : l.HasBasis pX sX) (hβ : (uniformity β).HasBasis pβ sβ) : TendstoUniformlyOn F f l s ↔ (∀ i, pβ i → ∃ j, pX j ∧ ∀ ⦃x⦄, x ∈ sX j → ∀ a ∈ s, (f a, F x a) ∈ sβ i) := by simp [hβ.tendstoUniformlyOn_iff_of_uniformity, hl.eventually_iff]
lemma
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_iff
An analogue of `Filter.HasBasis.tendsto_iff` for `TendstoUniformlyOn`.
tendstoUniformly_iff_of_uniformity {F : X → α → β} {f : α → β} {l : Filter X} {pβ : ιβ → Prop} {sβ : ιβ → Set (β × β)} (hβ : (uniformity β).HasBasis pβ sβ) : TendstoUniformly F f l ↔ (∀ i, pβ i → ∀ᶠ n in l, ∀ x, (f x, F n x) ∈ sβ i) := by simp_rw [← tendstoUniformlyOn_univ, hβ.tendstoUniformlyOn_iff_of_uniformity, mem_univ, true_imp_iff]
lemma
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformly_iff_of_uniformity
An analogue of `Filter.HasBasis.tendsto_right_iff` for `TendstoUniformly`.
tendstoUniformly_iff {F : X → α → β} {f : α → β} {l : Filter X} {pX : ιX → Prop} {sX : ιX → Set X} (hl : l.HasBasis pX sX) {pβ : ιβ → Prop} {sβ : ιβ → Set (β × β)} (hβ : (uniformity β).HasBasis pβ sβ) : TendstoUniformly F f l ↔ (∀ i, pβ i → ∃ j, pX j ∧ ∀ ⦃x⦄, x ∈ sX j → ∀ a, (f a, F x a) ∈ sβ i) := by simp only [hβ.tendstoUniformly_iff_of_uniformity, hl.eventually_iff]
lemma
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformly_iff
An analogue of `Filter.HasBasis.tendsto_iff` for `TendstoUniformly`.
UniformCauchySeqOnFilter (F : ι → α → β) (p : Filter ι) (p' : Filter α) : Prop := ∀ u ∈ 𝓤 β, ∀ᶠ m : (ι × ι) × α in (p ×ˢ p) ×ˢ p', (F m.fst.fst m.snd, F m.fst.snd m.snd) ∈ u
def
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOnFilter
A sequence is uniformly Cauchy if eventually all of its pairwise differences are uniformly bounded
UniformCauchySeqOn (F : ι → α → β) (p : Filter ι) (s : Set α) : Prop := ∀ u ∈ 𝓤 β, ∀ᶠ m : ι × ι in p ×ˢ p, ∀ x : α, x ∈ s → (F m.fst x, F m.snd x) ∈ u
def
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn
A sequence is uniformly Cauchy if eventually all of its pairwise differences are uniformly bounded
uniformCauchySeqOn_iff_uniformCauchySeqOnFilter : UniformCauchySeqOn F p s ↔ UniformCauchySeqOnFilter F p (𝓟 s) := by simp only [UniformCauchySeqOn, UniformCauchySeqOnFilter] refine forall₂_congr fun u hu => ?_ rw [eventually_prod_principal_iff]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
uniformCauchySeqOn_iff_uniformCauchySeqOnFilter
null
UniformCauchySeqOn.uniformCauchySeqOnFilter (hF : UniformCauchySeqOn F p s) : UniformCauchySeqOnFilter F p (𝓟 s) := by rwa [← uniformCauchySeqOn_iff_uniformCauchySeqOnFilter]
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.uniformCauchySeqOnFilter
null
TendstoUniformlyOnFilter.uniformCauchySeqOnFilter (hF : TendstoUniformlyOnFilter F f p p') : UniformCauchySeqOnFilter F p p' := by intro u hu rcases comp_symm_of_uniformity hu with ⟨t, ht, htsymm, htmem⟩ have := tendsto_swap4_prod.eventually ((hF t ht).prod_mk (hF t ht)) apply this.diag_of_prod_right.mono simp only [and_imp, Prod.forall] intro n1 n2 x hl hr exact Set.mem_of_mem_of_subset (prodMk_mem_compRel (htsymm hl) hr) htmem
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.uniformCauchySeqOnFilter
A sequence that converges uniformly is also uniformly Cauchy
TendstoUniformlyOn.uniformCauchySeqOn (hF : TendstoUniformlyOn F f p s) : UniformCauchySeqOn F p s := uniformCauchySeqOn_iff_uniformCauchySeqOnFilter.mpr hF.tendstoUniformlyOnFilter.uniformCauchySeqOnFilter
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.uniformCauchySeqOn
A sequence that converges uniformly is also uniformly Cauchy
UniformCauchySeqOnFilter.tendstoUniformlyOnFilter_of_tendsto (hF : UniformCauchySeqOnFilter F p p') (hF' : ∀ᶠ x : α in p', Tendsto (fun n => F n x) p (𝓝 (f x))) : TendstoUniformlyOnFilter F f p p' := by rcases p.eq_or_neBot with rfl | _ · simp only [TendstoUniformlyOnFilter, bot_prod, eventually_bot, implies_true] intro u hu rcases comp_symm_of_uniformity hu with ⟨t, ht, htsymm, htmem⟩ have hmc : ∀ᶠ x in (p ×ˢ p) ×ˢ p', Tendsto (fun n : ι => F n x.snd) p (𝓝 (f x.snd)) := by rw [eventually_prod_iff] exact ⟨fun _ => True, by simp, _, hF', by simp⟩ rw [Filter.eventually_swap_iff] have := tendsto_prodAssoc.eventually (tendsto_prod_swap.eventually ((hF t ht).and hmc)) apply this.curry.mono simp only [Equiv.prodAssoc_apply, eventually_and, eventually_const, Prod.snd_swap, Prod.fst_swap, and_imp, Prod.forall] intro x n hx hm' refine Set.mem_of_mem_of_subset (mem_compRel.mpr ?_) htmem rw [Uniform.tendsto_nhds_right] at hm' have := hx.and (hm' ht) obtain ⟨m, hm⟩ := this.exists exact ⟨F m x, ⟨hm.2, htsymm hm.1⟩⟩
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOnFilter.tendstoUniformlyOnFilter_of_tendsto
A uniformly Cauchy sequence converges uniformly to its limit
UniformCauchySeqOn.tendstoUniformlyOn_of_tendsto (hF : UniformCauchySeqOn F p s) (hF' : ∀ x : α, x ∈ s → Tendsto (fun n => F n x) p (𝓝 (f x))) : TendstoUniformlyOn F f p s := tendstoUniformlyOn_iff_tendstoUniformlyOnFilter.mpr (hF.uniformCauchySeqOnFilter.tendstoUniformlyOnFilter_of_tendsto hF')
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.tendstoUniformlyOn_of_tendsto
A uniformly Cauchy sequence converges uniformly to its limit
UniformCauchySeqOnFilter.mono_left {p'' : Filter ι} (hf : UniformCauchySeqOnFilter F p p') (hp : p'' ≤ p) : UniformCauchySeqOnFilter F p'' p' := fun u hu => (hf u hu).filter_mono (p'.prod_mono_left (Filter.prod_mono hp hp))
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOnFilter.mono_left
null
UniformCauchySeqOnFilter.mono_right {p'' : Filter α} (hf : UniformCauchySeqOnFilter F p p') (hp : p'' ≤ p') : UniformCauchySeqOnFilter F p p'' := fun u hu => have := (hf u hu).filter_mono ((p ×ˢ p).prod_mono_right hp) this.mono (by simp)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOnFilter.mono_right
null
UniformCauchySeqOn.mono (hf : UniformCauchySeqOn F p s) (hss' : s' ⊆ s) : UniformCauchySeqOn F p s' := by rw [uniformCauchySeqOn_iff_uniformCauchySeqOnFilter] at hf ⊢ exact hf.mono_right (le_principal_iff.mpr <| mem_principal.mpr hss')
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.mono
null
UniformCauchySeqOnFilter.comp {γ : Type*} (hf : UniformCauchySeqOnFilter F p p') (g : γ → α) : UniformCauchySeqOnFilter (fun n => F n ∘ g) p (p'.comap g) := fun u hu => by obtain ⟨pa, hpa, pb, hpb, hpapb⟩ := eventually_prod_iff.mp (hf u hu) rw [eventually_prod_iff] refine ⟨pa, hpa, pb ∘ g, ?_, fun hx _ hy => hpapb hx hy⟩ exact eventually_comap.mpr (hpb.mono fun x hx y hy => by simp only [hx, hy, Function.comp_apply])
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOnFilter.comp
Composing on the right by a function preserves uniform Cauchy sequences
UniformCauchySeqOn.comp {γ : Type*} (hf : UniformCauchySeqOn F p s) (g : γ → α) : UniformCauchySeqOn (fun n => F n ∘ g) p (g ⁻¹' s) := by rw [uniformCauchySeqOn_iff_uniformCauchySeqOnFilter] at hf ⊢ simpa only [UniformCauchySeqOn, comap_principal] using hf.comp g
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.comp
Composing on the right by a function preserves uniform Cauchy sequences
UniformContinuous.comp_uniformCauchySeqOn [UniformSpace γ] {g : β → γ} (hg : UniformContinuous g) (hf : UniformCauchySeqOn F p s) : UniformCauchySeqOn (fun n => g ∘ F n) p s := fun _u hu => hf _ (hg hu)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformContinuous.comp_uniformCauchySeqOn
Composing on the left by a uniformly continuous function preserves uniform Cauchy sequences
UniformCauchySeqOn.prodMap {ι' α' β' : Type*} [UniformSpace β'] {F' : ι' → α' → β'} {p' : Filter ι'} {s' : Set α'} (h : UniformCauchySeqOn F p s) (h' : UniformCauchySeqOn F' p' s') : UniformCauchySeqOn (fun i : ι × ι' => Prod.map (F i.1) (F' i.2)) (p ×ˢ p') (s ×ˢ s') := by intro u hu rw [uniformity_prod_eq_prod, mem_map, mem_prod_iff] at hu obtain ⟨v, hv, w, hw, hvw⟩ := hu simp_rw [mem_prod, and_imp, Prod.forall, Prod.map_apply] rw [← Set.image_subset_iff] at hvw apply (tendsto_swap4_prod.eventually ((h v hv).prod_mk (h' w hw))).mono intro x hx a b ha hb exact hvw ⟨_, mk_mem_prod (hx.1 a ha) (hx.2 b hb), rfl⟩ @[deprecated (since := "2025-03-10")] alias UniformCauchySeqOn.prod_map := UniformCauchySeqOn.prodMap
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.prodMap
null
UniformCauchySeqOn.prod {ι' β' : Type*} [UniformSpace β'] {F' : ι' → α → β'} {p' : Filter ι'} (h : UniformCauchySeqOn F p s) (h' : UniformCauchySeqOn F' p' s) : UniformCauchySeqOn (fun (i : ι × ι') a => (F i.fst a, F' i.snd a)) (p ×ˢ p') s := (congr_arg _ s.inter_self).mp ((h.prodMap h').comp fun a => (a, a))
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.prod
null
UniformCauchySeqOn.prod' {β' : Type*} [UniformSpace β'] {F' : ι → α → β'} (h : UniformCauchySeqOn F p s) (h' : UniformCauchySeqOn F' p s) : UniformCauchySeqOn (fun (i : ι) a => (F i a, F' i a)) p s := fun u hu => have hh : Tendsto (fun x : ι => (x, x)) p (p ×ˢ p) := tendsto_diag (hh.prodMap hh).eventually ((h.prod h') u hu)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.prod'
null
UniformCauchySeqOn.cauchy_map [hp : NeBot p] (hf : UniformCauchySeqOn F p s) (hx : x ∈ s) : Cauchy (map (fun i => F i x) p) := by simp only [cauchy_map_iff, hp, true_and] intro u hu rw [mem_map] filter_upwards [hf u hu] with p hp using hp x hx
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.cauchy_map
If a sequence of functions is uniformly Cauchy on a set, then the values at each point form a Cauchy sequence.
UniformCauchySeqOn.cauchySeq [Nonempty ι] [SemilatticeSup ι] (hf : UniformCauchySeqOn F atTop s) (hx : x ∈ s) : CauchySeq fun i ↦ F i x := hf.cauchy_map (hp := atTop_neBot) hx
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
UniformCauchySeqOn.cauchySeq
If a sequence of functions is uniformly Cauchy on a set, then the values at each point form a Cauchy sequence. See `UniformCauchySeqOn.cauchy_map` for the non-`atTop` case.
tendstoUniformlyOn_of_seq_tendstoUniformlyOn {l : Filter ι} [l.IsCountablyGenerated] (h : ∀ u : ℕ → ι, Tendsto u atTop l → TendstoUniformlyOn (fun n => F (u n)) f atTop s) : TendstoUniformlyOn F f l s := by rw [tendstoUniformlyOn_iff_tendsto, tendsto_iff_seq_tendsto] intro u hu rw [tendsto_prod_iff'] at hu specialize h (fun n => (u n).fst) hu.1 rw [tendstoUniformlyOn_iff_tendsto] at h exact h.comp (tendsto_id.prodMk hu.2)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_of_seq_tendstoUniformlyOn
null
TendstoUniformlyOn.seq_tendstoUniformlyOn {l : Filter ι} (h : TendstoUniformlyOn F f l s) (u : ℕ → ι) (hu : Tendsto u atTop l) : TendstoUniformlyOn (fun n => F (u n)) f atTop s := by rw [tendstoUniformlyOn_iff_tendsto] at h ⊢ exact h.comp ((hu.comp tendsto_fst).prodMk tendsto_snd)
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOn.seq_tendstoUniformlyOn
null
tendstoUniformlyOn_iff_seq_tendstoUniformlyOn {l : Filter ι} [l.IsCountablyGenerated] : TendstoUniformlyOn F f l s ↔ ∀ u : ℕ → ι, Tendsto u atTop l → TendstoUniformlyOn (fun n => F (u n)) f atTop s := ⟨TendstoUniformlyOn.seq_tendstoUniformlyOn, tendstoUniformlyOn_of_seq_tendstoUniformlyOn⟩
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformlyOn_iff_seq_tendstoUniformlyOn
null
tendstoUniformly_iff_seq_tendstoUniformly {l : Filter ι} [l.IsCountablyGenerated] : TendstoUniformly F f l ↔ ∀ u : ℕ → ι, Tendsto u atTop l → TendstoUniformly (fun n => F (u n)) f atTop := by simp_rw [← tendstoUniformlyOn_univ] exact tendstoUniformlyOn_iff_seq_tendstoUniformlyOn
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
tendstoUniformly_iff_seq_tendstoUniformly
null
TendstoUniformlyOnFilter.tendsto_of_eventually_tendsto (h1 : TendstoUniformlyOnFilter F f p p') (h2 : ∀ᶠ i in p, Tendsto (F i) p' (𝓝 (L i))) (h3 : Tendsto L p (𝓝 ℓ)) : Tendsto f p' (𝓝 ℓ) := by rw [tendsto_nhds_left] intro s hs rw [mem_map, Set.preimage, ← eventually_iff] obtain ⟨t, ht, hts⟩ := comp3_mem_uniformity hs have p1 : ∀ᶠ i in p, (L i, ℓ) ∈ t := tendsto_nhds_left.mp h3 ht have p2 : ∀ᶠ i in p, ∀ᶠ x in p', (F i x, L i) ∈ t := by filter_upwards [h2] with i h2 using tendsto_nhds_left.mp h2 ht have p3 : ∀ᶠ i in p, ∀ᶠ x in p', (f x, F i x) ∈ t := (h1 t ht).curry obtain ⟨i, p4, p5, p6⟩ := (p1.and (p2.and p3)).exists filter_upwards [p5, p6] with x p5 p6 using hts ⟨F i x, p6, L i, p5, p4⟩
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformlyOnFilter.tendsto_of_eventually_tendsto
null
TendstoUniformly.tendsto_of_eventually_tendsto (h1 : TendstoUniformly F f p) (h2 : ∀ᶠ i in p, Tendsto (F i) p' (𝓝 (L i))) (h3 : Tendsto L p (𝓝 ℓ)) : Tendsto f p' (𝓝 ℓ) := (h1.tendstoUniformlyOnFilter.mono_right le_top).tendsto_of_eventually_tendsto h2 h3
theorem
Topology
[ "Mathlib.Topology.UniformSpace.Cauchy" ]
Mathlib/Topology/UniformSpace/UniformConvergence.lean
TendstoUniformly.tendsto_of_eventually_tendsto
null
of the uniform structure of uniform convergence! Instead, we build a (not very interesting) Galois connection `UniformFun.gc` and then rely on the Galois connection API to do most of the work.
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
of
null
UniformFun (α β : Type*) := α → β
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
UniformFun
The type of functions from `α` to `β` equipped with the uniform structure and topology of uniform convergence. We denote it `α →ᵤ β`.
@[nolint unusedArguments] UniformOnFun (α β : Type*) (_ : Set (Set α)) := α → β @[inherit_doc] scoped[UniformConvergence] notation:25 α " →ᵤ " β:0 => UniformFun α β @[inherit_doc] scoped[UniformConvergence] notation:25 α " →ᵤ[" 𝔖 "] " β:0 => UniformOnFun α β 𝔖 open UniformConvergence variable {α β : Type*} {𝔖 : Set (Set α)}
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
UniformOnFun
The type of functions from `α` to `β` equipped with the uniform structure and topology of uniform convergence on some family `𝔖` of subsets of `α`. We denote it `α →ᵤ[𝔖] β`.
UniformFun.ofFun : (α → β) ≃ (α →ᵤ β) := ⟨fun x => x, fun x => x, fun _ => rfl, fun _ => rfl⟩
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
UniformFun.ofFun
Reinterpret `f : α → β` as an element of `α →ᵤ β`.
UniformOnFun.ofFun (𝔖) : (α → β) ≃ (α →ᵤ[𝔖] β) := ⟨fun x => x, fun x => x, fun _ => rfl, fun _ => rfl⟩
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
UniformOnFun.ofFun
Reinterpret `f : α → β` as an element of `α →ᵤ[𝔖] β`.
UniformFun.toFun : (α →ᵤ β) ≃ (α → β) := UniformFun.ofFun.symm
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
UniformFun.toFun
Reinterpret `f : α →ᵤ β` as an element of `α → β`.
UniformOnFun.toFun (𝔖) : (α →ᵤ[𝔖] β) ≃ (α → β) := (UniformOnFun.ofFun 𝔖).symm @[simp] lemma UniformFun.toFun_ofFun (f : α → β) : toFun (ofFun f) = f := rfl @[simp] lemma UniformFun.ofFun_toFun (f : α →ᵤ β) : ofFun (toFun f) = f := rfl @[simp] lemma UniformOnFun.toFun_ofFun (f : α → β) : toFun 𝔖 (ofFun 𝔖 f) = f := rfl @[simp] lemma UniformOnFun.ofFun_toFun (f : α →ᵤ[𝔖] β) : ofFun 𝔖 (toFun 𝔖 f) = f := rfl
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
UniformOnFun.toFun
Reinterpret `f : α →ᵤ[𝔖] β` as an element of `α → β`.
protected gen (V : Set (β × β)) : Set ((α →ᵤ β) × (α →ᵤ β)) := { uv : (α →ᵤ β) × (α →ᵤ β) | ∀ x, (toFun uv.1 x, toFun uv.2 x) ∈ V }
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
gen
Basis sets for the uniformity of uniform convergence: `gen α β V` is the set of pairs `(f, g)` of functions `α →ᵤ β` such that `∀ x, (f x, g x) ∈ V`.
protected isBasis_gen (𝓑 : Filter <| β × β) : IsBasis (fun V : Set (β × β) => V ∈ 𝓑) (UniformFun.gen α β) := ⟨⟨univ, univ_mem⟩, @fun U V hU hV => ⟨U ∩ V, inter_mem hU hV, fun _ huv => ⟨fun x => (huv x).left, fun x => (huv x).right⟩⟩⟩
theorem
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
isBasis_gen
If `𝓕` is a filter on `β × β`, then the set of all `UniformFun.gen α β V` for `V ∈ 𝓕` is a filter basis on `(α →ᵤ β) × (α →ᵤ β)`. This will only be applied to `𝓕 = 𝓤 β` when `β` is equipped with a `UniformSpace` structure, but it is useful to define it for any filter in order to be able to state that it has a lower adjoint (see `UniformFun.gc`).
protected basis (𝓕 : Filter <| β × β) : FilterBasis ((α →ᵤ β) × (α →ᵤ β)) := (UniformFun.isBasis_gen α β 𝓕).filterBasis
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
basis
For `𝓕 : Filter (β × β)`, this is the set of all `UniformFun.gen α β V` for `V ∈ 𝓕` as a bundled `FilterBasis` over `(α →ᵤ β) × (α →ᵤ β)`. This will only be applied to `𝓕 = 𝓤 β` when `β` is equipped with a `UniformSpace` structure, but it is useful to define it for any filter in order to be able to state that it has a lower adjoint (see `UniformFun.gc`).
protected filter (𝓕 : Filter <| β × β) : Filter ((α →ᵤ β) × (α →ᵤ β)) := (UniformFun.basis α β 𝓕).filter
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
filter
For `𝓕 : Filter (β × β)`, this is the filter generated by the filter basis `UniformFun.basis α β 𝓕`. For `𝓕 = 𝓤 β`, this will be the uniformity of uniform convergence on `α`.
protected phi (α β : Type*) (uvx : ((α →ᵤ β) × (α →ᵤ β)) × α) : β × β := (uvx.fst.fst uvx.2, uvx.1.2 uvx.2) set_option quotPrecheck false -- Porting note: we need a `[quot_precheck]` instance on fbinop% /- This is a lower adjoint to `UniformFun.filter` (see `UniformFun.gc`). The exact definition of the lower adjoint `l` is not interesting; we will only use that it exists (in `UniformFun.mono` and `UniformFun.iInf_eq`) and that `l (Filter.map (Prod.map f f) 𝓕) = Filter.map (Prod.map ((∘) f) ((∘) f)) (l 𝓕)` for each `𝓕 : Filter (γ × γ)` and `f : γ → α` (in `UniformFun.comap_eq`). -/ local notation "lowerAdjoint" => fun 𝓐 => map (UniformFun.phi α β) (𝓐 ×ˢ ⊤)
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
phi
null
protected gc : GaloisConnection lowerAdjoint fun 𝓕 => UniformFun.filter α β 𝓕 := by intro 𝓐 𝓕 symm calc 𝓐 ≤ UniformFun.filter α β 𝓕 ↔ (UniformFun.basis α β 𝓕).sets ⊆ 𝓐.sets := by rw [UniformFun.filter, ← FilterBasis.generate, le_generate_iff] _ ↔ ∀ U ∈ 𝓕, UniformFun.gen α β U ∈ 𝓐 := image_subset_iff _ ↔ ∀ U ∈ 𝓕, { uv | ∀ x, (uv, x) ∈ { t : ((α →ᵤ β) × (α →ᵤ β)) × α | (t.1.1 t.2, t.1.2 t.2) ∈ U } } ∈ 𝓐 := Iff.rfl _ ↔ ∀ U ∈ 𝓕, { uvx : ((α →ᵤ β) × (α →ᵤ β)) × α | (uvx.1.1 uvx.2, uvx.1.2 uvx.2) ∈ U } ∈ 𝓐 ×ˢ (⊤ : Filter α) := forall₂_congr fun U _hU => mem_prod_top.symm _ ↔ lowerAdjoint 𝓐 ≤ 𝓕 := Iff.rfl variable [UniformSpace β]
theorem
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
gc
The function `UniformFun.filter α β : Filter (β × β) → Filter ((α →ᵤ β) × (α →ᵤ β))` has a lower adjoint `l` (in the sense of `GaloisConnection`). The exact definition of `l` is not interesting; we will only use that it exists (in `UniformFun.mono` and `UniformFun.iInf_eq`) and that `l (Filter.map (Prod.map f f) 𝓕) = Filter.map (Prod.map ((∘) f) ((∘) f)) (l 𝓕)` for each `𝓕 : Filter (γ × γ)` and `f : γ → α` (in `UniformFun.comap_eq`).
protected uniformCore : UniformSpace.Core (α →ᵤ β) := UniformSpace.Core.mkOfBasis (UniformFun.basis α β (𝓤 β)) (fun _ ⟨_, hV, hVU⟩ _ => hVU ▸ fun _ => refl_mem_uniformity hV) (fun _ ⟨V, hV, hVU⟩ => hVU ▸ ⟨UniformFun.gen α β (Prod.swap ⁻¹' V), ⟨Prod.swap ⁻¹' V, tendsto_swap_uniformity hV, rfl⟩, fun _ huv x => huv x⟩) fun _ ⟨_, hV, hVU⟩ => hVU ▸ let ⟨W, hW, hWV⟩ := comp_mem_uniformity_sets hV ⟨UniformFun.gen α β W, ⟨W, hW, rfl⟩, fun _ ⟨w, huw, hwv⟩ x => hWV ⟨w x, ⟨huw x, hwv x⟩⟩⟩
def
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
uniformCore
Core of the uniform structure of uniform convergence.
uniformSpace : UniformSpace (α →ᵤ β) := UniformSpace.ofCore (UniformFun.uniformCore α β)
instance
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
uniformSpace
Uniform structure of uniform convergence, declared as an instance on `α →ᵤ β`. We will denote it `𝒰(α, β, uβ)` in the rest of this file.
topologicalSpace : TopologicalSpace (α →ᵤ β) := inferInstance local notation "𝒰(" α ", " β ", " u ")" => @UniformFun.uniformSpace α β u
instance
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
topologicalSpace
Topology of uniform convergence, declared as an instance on `α →ᵤ β`.
protected hasBasis_uniformity : (𝓤 (α →ᵤ β)).HasBasis (· ∈ 𝓤 β) (UniformFun.gen α β) := (UniformFun.isBasis_gen α β (𝓤 β)).hasBasis
theorem
Topology
[ "Mathlib.Topology.Coherent", "Mathlib.Topology.UniformSpace.Equiv", "Mathlib.Topology.UniformSpace.Pi", "Mathlib.Topology.UniformSpace.UniformApproximation" ]
Mathlib/Topology/UniformSpace/UniformConvergenceTopology.lean
hasBasis_uniformity
By definition, the uniformity of `α →ᵤ β` admits the family `{(f, g) | ∀ x, (f x, g x) ∈ V}` for `V ∈ 𝓤 β` as a filter basis.