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style(Immersion): tweak newlines; use notation for uncurry.
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grunweg committed Mar 18, 2024
1 parent 78b4d50 commit bfd0afb
Showing 1 changed file with 4 additions and 10 deletions.
14 changes: 4 additions & 10 deletions SphereEversion/Global/Immersion.lean
Original file line number Diff line number Diff line change
Expand Up @@ -26,21 +26,15 @@ variable {E : Type*} [NormedAddCommGroup E] [NormedSpace ℝ E]
(N : Type*) [TopologicalSpace N] [ChartedSpace G N] [SmoothManifoldWithCorners J N]

local notation "TM" => TangentSpace I

local notation "TM'" => TangentSpace I'

local notation "HJ" => ModelProd (ModelProd H H') (E →L[ℝ] E')

local notation "ψJ" => chartAt HJ

variable (M M')

variable (M M') in
/-- The relation of immersions for maps between two manifolds. -/
def immersionRel : RelMfld I M I' M' :=
{σ | Injective σ.2}

variable {M M'}

@[simp]
theorem mem_immersionRel_iff {σ : OneJetBundle I M I' M'} :
σ ∈ immersionRel I M I' M' ↔ Injective (σ.2 : TangentSpace I _ →L[ℝ] TangentSpace I' _) :=
Expand Down Expand Up @@ -272,7 +266,7 @@ theorem ContDiff.uncurry_left' (n : ℕ∞) {f : E × F → G}
ContDiff 𝕜 n (fun p : F ↦ f ⟨x, p⟩) :=
hf.comp (ContDiff.inr x n)

theorem ContDiff.uncurry_left {f : E → F → G} (n : ℕ∞) (hf : ContDiff 𝕜 n (uncurry f)) (x : E) :
theorem ContDiff.uncurry_left {f : E → F → G} (n : ℕ∞) (hf : ContDiff 𝕜 n ↿f) (x : E) :
ContDiff 𝕜 n (f x) := by
have : f x = (uncurry f) ∘ fun p : F ↦ (⟨x, p⟩ : E × F) := by ext; simp
rw [this] ; exact hf.comp (ContDiff.inr x n)
Expand All @@ -299,7 +293,7 @@ alias Smooth.prod_left := Smooth.inr

-- move to Mathlib.Geometry.Manifold.ContMDiff.Product
theorem Smooth.uncurry_left
{f : M → M' → P} (hf : Smooth (I.prod I') IP (uncurry f)) (x : M) :
{f : M → M' → P} (hf : Smooth (I.prod I') IP ↿f) (x : M) :
Smooth I' IP (f x) := by
have : f x = (uncurry f) ∘ fun p : M' ↦ ⟨x, p⟩ := by ext; simp
-- or just `apply hf.comp (Smooth.inr I I' x)`
Expand All @@ -309,7 +303,7 @@ end helper

theorem sphere_eversion :
∃ f : ℝ → 𝕊² → E,
ContMDiff (𝓘(ℝ, ℝ).prod (𝓡 2)) 𝓘(ℝ, E) ∞ (uncurry f)
ContMDiff (𝓘(ℝ, ℝ).prod (𝓡 2)) 𝓘(ℝ, E) ∞ ↿f
(f 0 = fun x : 𝕊² ↦ (x : E)) ∧ (f 1 = fun x : 𝕊² ↦ -(x : E)) ∧
∀ t, Immersion (𝓡 2) 𝓘(ℝ, E) (f t) ⊤ := by
classical
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