From 969703c7fb5b8d1c8b8de4ca9ec7c3c8a4237b26 Mon Sep 17 00:00:00 2001 From: "Yury G. Kudryashov" Date: Tue, 8 Dec 2020 19:32:59 -0500 Subject: [PATCH] Snapshot --- src/topology/algebra/ordered.lean | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/src/topology/algebra/ordered.lean b/src/topology/algebra/ordered.lean index 2887cf99f11fd..8a9d9ef3760c9 100644 --- a/src/topology/algebra/ordered.lean +++ b/src/topology/algebra/ordered.lean @@ -299,8 +299,8 @@ end /-- Intermediate value theorem for two functions: if `f` and `g` are two functions continuous on a preconnected set `s` and for some `a b ∈ s` we have `f a ≤ g a` and `g b ≤ f b`, then for some `x ∈ s` we have `f x = g x`. -/ -lemma is_preconnected.intermediate_value₂ {s : set γ} - (hs : is_preconnected s) {a b : γ} (ha : a ∈ s) (hb : b ∈ s) {f g : γ → α} +lemma is_preconnected.intermediate_value₂ {s : set γ} (hs : is_preconnected s) + {a b : γ} (ha : a ∈ s) (hb : b ∈ s) {f g : γ → α} (hf : continuous_on f s) (hg : continuous_on g s) (ha' : f a ≤ g a) (hb' : g b ≤ f b) : ∃ x ∈ s, f x = g x := let ⟨x, hx⟩ := @intermediate_value_univ₂ α s _ _ _ _ (subtype.preconnected_space hs) ⟨a, ha⟩ ⟨b, hb⟩ @@ -309,21 +309,19 @@ let ⟨x, hx⟩ := @intermediate_value_univ₂ α s _ _ _ _ (subtype.preconnecte in ⟨x, x.2, hx⟩ /-- Intermediate Value Theorem for continuous functions on connected sets. -/ -lemma is_preconnected.intermediate_value {γ : Type*} [topological_space γ] {s : set γ} - (hs : is_preconnected s) {a b : γ} (ha : a ∈ s) (hb : b ∈ s) {f : γ → α} - (hf : continuous_on f s) : +lemma is_preconnected.intermediate_value {s : set γ} (hs : is_preconnected s) + {a b : γ} (ha : a ∈ s) (hb : b ∈ s) {f : γ → α} (hf : continuous_on f s) : Icc (f a) (f b) ⊆ f '' s := λ x hx, mem_image_iff_bex.2 $ hs.intermediate_value₂ ha hb hf continuous_on_const hx.1 hx.2 /-- Intermediate Value Theorem for continuous functions on connected spaces. -/ -lemma intermediate_value_univ {γ : Type*} [topological_space γ] [preconnected_space γ] - (a b : γ) {f : γ → α} (hf : continuous f) : +lemma intermediate_value_univ [preconnected_space γ] (a b : γ) {f : γ → α} (hf : continuous f) : Icc (f a) (f b) ⊆ range f := λ x hx, intermediate_value_univ₂ hf continuous_const hx.1 hx.2 /-- Intermediate Value Theorem for continuous functions on connected spaces. -/ -lemma mem_range_of_exists_le_of_exists_ge {γ : Type*} [topological_space γ] [preconnected_space γ] - {c : α} {f : γ → α} (hf : continuous f) (h₁ : ∃ a, f a ≤ c) (h₂ : ∃ b, c ≤ f b) : +lemma mem_range_of_exists_le_of_exists_ge [preconnected_space γ] {c : α} {f : γ → α} + (hf : continuous f) (h₁ : ∃ a, f a ≤ c) (h₂ : ∃ b, c ≤ f b) : c ∈ range f := let ⟨a, ha⟩ := h₁, ⟨b, hb⟩ := h₂ in intermediate_value_univ a b hf ⟨ha, hb⟩