roseking's picture
Add lean source and binary files (part 17)
ddc84c5 verified
Raw History Blame Contribute Delete
2.88 kB
import Mathlib
namespace OAI
noncomputable section
open MeasureTheory Filter Set
open scoped ENNReal NNReal Topology
universe uX u_1
namespace ExactModuli
variable {X : Type uX} [NormedAddCommGroup X] [NormedSpace ℝ X]
/-- Closed linear subspaces of finite codimension. -/
def Cofinite (F : Submodule ℝ X) : Prop :=
IsClosed (F : Set X) ∧ FiniteDimensional ℝ (X ⧸ F)
/-- Averaged increment for directions of norm at least one. -/
def averagedIncrement (N : Seminorm ℝ X) (x : X) (t : ℝ) (y : X) : ℝ :=
(N (x + t • y) + N (x - t • y)) / 2 - 1
def H (N : Seminorm ℝ X) (x : X) (t : ℝ) : ℝ :=
sSup {r | ∃ F : Submodule ℝ X, Cofinite F ∧
r = sInf {a | ∃ y ∈ F, 1 ≤ N y ∧ a = averagedIncrement N x t y}}
def D (N : Seminorm ℝ X) (x : X) (t : ℝ) : ℝ :=
sSup {r | ∃ F : Submodule ℝ X, Cofinite F ∧
r = sInf {a | ∃ y ∈ F, N y = 1 ∧ a = N (x + t • y) - 1}}
def averagedModulus (N : Seminorm ℝ X) (t : ℝ) : ℝ :=
sInf {r | ∃ x, N x = 1 ∧ r = H N x t}
def oneSidedModulus (N : Seminorm ℝ X) (t : ℝ) : ℝ :=
sInf {r | ∃ x, N x = 1 ∧ r = D N x t}
/-- Two-sided comparison makes this seminorm a genuine norm equivalent to the original. -/
def EquivalentNorm (N : Seminorm ℝ X) : Prop :=
∃ a b : ℝ, 0 < a ∧ 0 < b ∧ ∀ x, a * ‖x‖ ≤ N x ∧ N x ≤ b * ‖x‖
def AUC (N : Seminorm ℝ X) : Prop :=
∀ t : ℝ, 0 < t → 0 < oneSidedModulus N t
/-- Every rank-one operator has the form `ell.smulRight v`. -/
def Daugavet (X : Type uX) [NormedAddCommGroup X] [NormedSpace ℝ X] : Prop :=
∀ (ell : X →L[ℝ] ℝ) (v : X),
‖ContinuousLinearMap.id ℝ X + ell.smulRight v‖ = 1 + ‖ell.smulRight v‖
variable {Ω : Type u_1} [MeasurableSpace Ω] (μ : Measure Ω)
/-- Convergence-in-measure distance on L1 equivalence classes. -/
def measureDistance (f g : Lp ℝ 1 μ) : ℝ :=
sInf {a : ℝ | 0 < a ∧ μ.real {ω | a < |f ω - g ω|} < a}
/-- Finite covers of the entire unit ball in convergence-in-measure distance. -/
def MeasurePrecompactBall (E : Submodule ℝ (Lp ℝ 1 μ)) : Prop :=
∀ ε : ℝ, 0 < ε → ∃ s : Finset (Lp ℝ 1 μ),
∀ y : E, ‖y‖ ≤ 1 → ∃ b ∈ s, measureDistance μ (y : Lp ℝ 1 μ) b < ε
/-- Every nonempty unit-ball slice contains an almost antipodal unit vector. -/
def UnitSliceProperty (X : Type uX) [NormedAddCommGroup X] [NormedSpace ℝ X] : Prop :=
∀ (w : X), ‖w‖ = 1 → ∀ (ell : X →L[ℝ] ℝ) (α : ℝ),
(∃ u : X, ‖u‖ ≤ 1 ∧ α < ell u) →
∀ ρ : ℝ, 0 < ρ → ∃ y : X, ‖y‖ = 1 ∧ α < ell y ∧ 2 - ρ ≤ ‖w + y‖
/-- The countable product of unit intervals. -/
abbrev KWOmega := ℕ → unitInterval
def kwMeasure : Measure KWOmega := Measure.infinitePi (fun _ : ℕ => (volume : Measure unitInterval))
end ExactModuli
end
end OAI