Wkp U e Norm eq zero of ae zero
WkpU.eNorm_eq_zero_of_ae_zero
Plain-language statement
If f : WkpU d k p U hU is almost everywhere zero on U, then its Sobolev eNorm is zero.
Exact Lean statement
lemma WkpU.eNorm_eq_zero_of_ae_zero (hp : p ≠ 0) (f : WkpU d k p U hU)
(hf : (↑↑↑f : (Fin d → ℝ) → ℝ) =ᶠ[ae (μU d U)] 0) :
WkpU.eNorm k p f = 0Formal artifact
Lean source
lemma WkpU.eNorm_eq_zero_of_ae_zero (hp : p ≠ 0) (f : WkpU d k p U hU) (hf : (↑↑↑f : (Fin d → ℝ) → ℝ) =ᶠ[ae (μU d U)] 0) : WkpU.eNorm k p f = 0 := by have h_zero : ∀ n s, WkpU.derivELpNorm f n s = 0 := by intro n s cases n with | zero => exact (eLpNorm_congr_ae hf).trans eLpNorm_zero | succ m => dsimp only [WkpU.derivELpNorm] split_ifs with hnk · have hweak0 : (WkpU.weakDeriv f ⟨m+1, Nat.succ_pos _⟩ hnk s) =ᵐ[μU d U] (0 : (Fin d → ℝ) →ₘ[μU d U] ℝ) := by apply WeakmultiderivU_unique hU s f.val _ 0 intro ψ hψ rw [integral_smul_aezero_tsupport hU.measurableSet hf (FderivCcinfty s hψ).2.1] have hint : ∫ x : Fin ↑d → ℝ, ψ x • ((0 : ((Fin ↑d → ℝ) →ₘ[μU d U] ℝ)) x) ∂ μU d U = 0 := by apply integral_eq_zero_of_ae filter_upwards [AEEqFun.coeFn_zero (α := Fin ↑d → ℝ) (μ := μU d U) (β := ℝ)] with x hx simp [hx] simpa [smul_eq_mul] using hint rw [eLpNorm_congr_ae (hweak0.trans AEEqFun.coeFn_zero)] exact eLpNorm_zero · rfl simp only [WkpU.eNorm] split_ifs with h_top · simp [h_zero] · have p_pos : 0 < p.toReal := ENNReal.toReal_pos hp h_top simp [h_zero, ENNReal.zero_rpow_of_pos p_pos, p_pos]- Project
- PDE
- License
- Apache-2.0
- Commit
- 0ab5d79a0d7a
- Source
- PDE/SobolevSpace/SobolevSpaces.lean:176-208
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