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Atlas.DifferentialAnalysis.code.WavefrontSetProducts

theorem WavefrontSet.not_mem_css_zero {n : ℕ} (p : ClosedBall n) :
p ∉ Css 0

The zero tempered distribution has empty conic singular support: any p lies outside Css 0.

The Fourier transform of zero is zero, so its conic singular support is empty.

theorem WavefrontSet.css_subadditive_not_mem {n : ℕ} {u₁ u₂ : TemperedDistribution (EuclideanSpace ℝ (Fin n)) ℂ} {p : ClosedBall n} (h₁ : p ∉ Css u₁) (h₂ : p ∉ Css u₂) :
p ∉ Css (u₁ + u₂)

Subadditivity of the conic singular support: if p ∉ Css u₁ and p ∉ Css u₂, then p ∉ Css (u₁ + u₂).

If p lies outside Css u, then (p, q) lies outside WFsc u for any boundary pair (p, q).

If q lies outside Css (𝓕 u), then (p, q) lies outside WFsc u for any boundary pair (p, q).

theorem WavefrontSet.wfsc_subadditive' {n : ℕ} (u₁ u₂ : TemperedDistribution (EuclideanSpace ℝ (Fin n)) ℂ) (p q : ClosedBall n) (h₁ : (p, q) ∉ WFsc u₁) (h₂ : (p, q) ∉ WFsc u₂) :
(p, q) ∉ WFsc (u₁ + u₂)

Subadditivity of the scattering wavefront set: if (p, q) ∉ WFsc u₁ and (p, q) ∉ WFsc u₂, then (p, q) ∉ WFsc (u₁ + u₂).

If (p, q) ∉ WFsc u, then u decomposes as u₁ + u₂ with p ∉ Css u₁ and q ∉ Css (𝓕 u₂).

Equivalence (Melrose Thm 12.18-style): (p, q) ∉ WFsc u iff u decomposes into pieces avoiding p in physical and q in Fourier conic singular support.