From 3e282876aa45d0723aecf81c2eea05c0b24a573e Mon Sep 17 00:00:00 2001 From: Pietro Monticone <38562595+pitmonticone@users.noreply.github.com> Date: Mon, 24 Jun 2024 03:28:01 +0200 Subject: [PATCH 1/4] feat(Topology/UniformSpace): add `uniformContinuous_ite ` This PR adds the theorem `uniformContinuous_ite`. Co-Authored-By: D-Thomine <100795491+D-Thomine@users.noreply.github.com> --- Mathlib/Topology/UniformSpace/Basic.lean | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Mathlib/Topology/UniformSpace/Basic.lean b/Mathlib/Topology/UniformSpace/Basic.lean index 1e14413fa5818a..e8701e94f721e9 100644 --- a/Mathlib/Topology/UniformSpace/Basic.lean +++ b/Mathlib/Topology/UniformSpace/Basic.lean @@ -1120,6 +1120,13 @@ nonrec theorem UniformContinuous.comp [UniformSpace β] [UniformSpace γ] {g : hg.comp hf #align uniform_continuous.comp UniformContinuous.comp +theorem uniformContinuous_ite [UniformSpace β] (T : β → β) (n : ℕ) (h : UniformContinuous T) : + UniformContinuous T^[n] := by + induction' n with n hn + · exact uniformContinuous_id + · exact Function.iterate_succ _ _ ▸ UniformContinuous.comp hn h +#align uniform_continuous_ite uniformContinuous_ite + theorem Filter.HasBasis.uniformContinuous_iff {ι'} [UniformSpace β] {p : ι → Prop} {s : ι → Set (α × α)} (ha : (𝓤 α).HasBasis p s) {q : ι' → Prop} {t : ι' → Set (β × β)} (hb : (𝓤 β).HasBasis q t) {f : α → β} : From e40de6c3a4dde95dde54c30c35d533390ec2e009 Mon Sep 17 00:00:00 2001 From: Pietro Monticone <38562595+pitmonticone@users.noreply.github.com> Date: Mon, 24 Jun 2024 03:30:33 +0200 Subject: [PATCH 2/4] Update Basic.lean Co-Authored-By: D-Thomine <100795491+D-Thomine@users.noreply.github.com> --- Mathlib/Topology/UniformSpace/Basic.lean | 2 ++ 1 file changed, 2 insertions(+) diff --git a/Mathlib/Topology/UniformSpace/Basic.lean b/Mathlib/Topology/UniformSpace/Basic.lean index e8701e94f721e9..c85e9d0c94780c 100644 --- a/Mathlib/Topology/UniformSpace/Basic.lean +++ b/Mathlib/Topology/UniformSpace/Basic.lean @@ -1120,6 +1120,8 @@ nonrec theorem UniformContinuous.comp [UniformSpace β] [UniformSpace γ] {g : hg.comp hf #align uniform_continuous.comp UniformContinuous.comp +/--If a function `T` is uniformly continuous in a uniform space `β`, +then its `n`-th iterate `T^[n]` is also uniformly continuous.-/ theorem uniformContinuous_ite [UniformSpace β] (T : β → β) (n : ℕ) (h : UniformContinuous T) : UniformContinuous T^[n] := by induction' n with n hn From 2fd6a01761e7ad67aba9a7e7e1b6fff5e72697ba Mon Sep 17 00:00:00 2001 From: Pietro Monticone <38562595+pitmonticone@users.noreply.github.com> Date: Mon, 24 Jun 2024 16:55:39 +0200 Subject: [PATCH 3/4] Update Basic.lean --- Mathlib/Topology/UniformSpace/Basic.lean | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/Mathlib/Topology/UniformSpace/Basic.lean b/Mathlib/Topology/UniformSpace/Basic.lean index c85e9d0c94780c..cb67b5c6f18fe8 100644 --- a/Mathlib/Topology/UniformSpace/Basic.lean +++ b/Mathlib/Topology/UniformSpace/Basic.lean @@ -1122,12 +1122,11 @@ nonrec theorem UniformContinuous.comp [UniformSpace β] [UniformSpace γ] {g : /--If a function `T` is uniformly continuous in a uniform space `β`, then its `n`-th iterate `T^[n]` is also uniformly continuous.-/ -theorem uniformContinuous_ite [UniformSpace β] (T : β → β) (n : ℕ) (h : UniformContinuous T) : +theorem UniformContinuous.iterate [UniformSpace β] (T : β → β) (n : ℕ) (h : UniformContinuous T) : UniformContinuous T^[n] := by induction' n with n hn · exact uniformContinuous_id · exact Function.iterate_succ _ _ ▸ UniformContinuous.comp hn h -#align uniform_continuous_ite uniformContinuous_ite theorem Filter.HasBasis.uniformContinuous_iff {ι'} [UniformSpace β] {p : ι → Prop} {s : ι → Set (α × α)} (ha : (𝓤 α).HasBasis p s) {q : ι' → Prop} {t : ι' → Set (β × β)} From 4f488578caa345cec9b61b8870584e8835e8511c Mon Sep 17 00:00:00 2001 From: Pietro Monticone <38562595+pitmonticone@users.noreply.github.com> Date: Mon, 24 Jun 2024 18:37:35 +0200 Subject: [PATCH 4/4] Update Basic.lean --- Mathlib/Topology/UniformSpace/Basic.lean | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/Mathlib/Topology/UniformSpace/Basic.lean b/Mathlib/Topology/UniformSpace/Basic.lean index cb67b5c6f18fe8..0f3467989592ee 100644 --- a/Mathlib/Topology/UniformSpace/Basic.lean +++ b/Mathlib/Topology/UniformSpace/Basic.lean @@ -1124,9 +1124,9 @@ nonrec theorem UniformContinuous.comp [UniformSpace β] [UniformSpace γ] {g : then its `n`-th iterate `T^[n]` is also uniformly continuous.-/ theorem UniformContinuous.iterate [UniformSpace β] (T : β → β) (n : ℕ) (h : UniformContinuous T) : UniformContinuous T^[n] := by - induction' n with n hn - · exact uniformContinuous_id - · exact Function.iterate_succ _ _ ▸ UniformContinuous.comp hn h + induction n with + | zero => exact uniformContinuous_id + | succ n hn => exact Function.iterate_succ _ _ ▸ UniformContinuous.comp hn h theorem Filter.HasBasis.uniformContinuous_iff {ι'} [UniformSpace β] {p : ι → Prop} {s : ι → Set (α × α)} (ha : (𝓤 α).HasBasis p s) {q : ι' → Prop} {t : ι' → Set (β × β)}