OAI/Geometry/RCD/Sobolev/DirichletMaximum.lean

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Weak maximum principle for the constructed Dirichlet solutions

  1. theorem OAI.RegularPointCoordinates.dirichlet_solution_nonneg line 19

    Source documentation

    A Dirichlet solution of a nonnegative functional is nonnegative. The proof uses the actual positive-part contraction and its energy inequality.

    theorem dirichlet_solution_nonneg (Ω : Set X) {P : ℝ} (hP : 0 ≤ P)
        (hbound : ∀ f : SobolevSpace.dirichlet μ hQ Ω,
          ‖SobolevSpace.toLp μ hQ f.val‖ ^ 2 ≤ P * energyForm μ hQ f.val f.val)
        (F : SobolevSpace.dirichlet μ hQ Ω →L[ℝ] ℝ)
        (hpositive : ∀ φ : SobolevSpace.dirichlet μ hQ Ω,
          (∀ᵐ x ∂μ, 0 ≤ SobolevSpace.toLp μ hQ φ.val x) → 0 ≤ F φ)
        (f : SobolevSpace.dirichlet μ hQ Ω)
        (hsolve : ∀ φ : SobolevSpace.dirichlet μ hQ Ω,
          energyForm μ hQ f.val φ.val = F φ) :
        ∀ᵐ x ∂μ, 0 ≤ SobolevSpace.toLp μ hQ f.val x := by
    …

    Mentions: OAI.RegularPointCoordinates.SobolevSpace.dirichlet, OAI.RegularPointCoordinates.SobolevSpace.toLp, OAI.RegularPointCoordinates.energyForm

  2. theorem OAI.RegularPointCoordinates.exists_nonnegative_dirichlet_solution line 71

    Source documentation

    The positive solution exists for every positive continuous source.

    theorem exists_nonnegative_dirichlet_solution (Ω : Set X) {P : ℝ} (hP : 0 ≤ P)
        (hbound : ∀ f : SobolevSpace.dirichlet μ hQ Ω,
          ‖SobolevSpace.toLp μ hQ f.val‖ ^ 2 ≤ P * energyForm μ hQ f.val f.val)
        (F : SobolevSpace.dirichlet μ hQ Ω →L[ℝ] ℝ)
        (hpositive : ∀ φ : SobolevSpace.dirichlet μ hQ Ω,
          (∀ᵐ x ∂μ, 0 ≤ SobolevSpace.toLp μ hQ φ.val x) → 0 ≤ F φ) :
        ∃ f : SobolevSpace.dirichlet μ hQ Ω,
          (∀ φ : SobolevSpace.dirichlet μ hQ Ω,
            energyForm μ hQ f.val φ.val = F φ) ∧
          (∀ᵐ x ∂μ, 0 ≤ SobolevSpace.toLp μ hQ f.val x) := by
    …

    Mentions: OAI.RegularPointCoordinates.SobolevSpace.dirichlet, OAI.RegularPointCoordinates.SobolevSpace.toLp, OAI.RegularPointCoordinates.energyForm