openAI-math-dataset / lean /OAI /Geometry /SmoothYau /Estimates /FiniteSumTsupportSubset.lean
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import Mathlib
import OAI.Geometry.SmoothYau.Smoothness.NormIteratedFDerivCompLinear
namespace OAI
noncomputable section
open Set Filter MeasureTheory ProbabilityTheory
open scoped Topology ContDiff ENNReal
namespace YauCounterexamples
lemma finite_sum_tsupport_subset {E I : Type*} [TopologicalSpace E]
{V : Set E} (s : Finset I) (f : I → E → ℝ)
(hf : ∀ i ∈ s, tsupport (f i) ⊆ V) :
tsupport (fun x => ∑ i ∈ s, f i x) ⊆ V := by
classical
induction s using Finset.induction_on with
| empty => simp
| @insert a s ha ih =>
simp only [Finset.sum_insert ha]
exact (tsupport_add _ _).trans (union_subset (hf a (Finset.mem_insert_self _ _))
(ih (fun i hi => hf i (Finset.mem_insert_of_mem hi))))
lemma finiteWaveSuperposition_tsupport {E I : Type*} [TopologicalSpace E] [Fintype I]
{O : Set E} {U : I → Fin 3 → E → ℂ}
(hU : ∀ i ℓ, tsupport (U i ℓ) ⊆ O) (γ : I → Fin 3 → ℂ) :
tsupport (finiteWaveSuperposition (fun _ => (0 : ℝ)) U γ) ⊆ O := by
classical
have he : finiteWaveSuperposition (fun _ => (0 : ℝ)) U γ =
fun x => ∑ i, ∑ ℓ, (γ i ℓ*U i ℓ x).re := by
funext x; exact zero_add _
rw [he]
apply finite_sum_tsupport_subset
intro i _
apply finite_sum_tsupport_subset
intro ℓ _
exact (tsupport_comp_subset (g := Complex.re) rfl (fun x => γ i ℓ*U i ℓ x)).trans
(tsupport_mul_subset_right.trans (hU i ℓ))
end YauCounterexamples
end
end OAI