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TauCeti.Topology.Compactness.Normed

Uniform local norm bounds over compact parameter spaces #

This file records a uniform local boundedness consequence of continuity over a compact family.

Main declarations #

theorem TauCeti.exists_eventually_norm_le_compact_family {X : Type u_1} {P : Type u_2} {α : Type u_3} {H : Type u_4} [TopologicalSpace X] [TopologicalSpace P] [TopologicalSpace α] [CompactSpace α] [NormedAddCommGroup H] {W : Set (X × P)} {F : X × P → H} {ι : α → P} (hι : Continuous ι) (hW : IsOpen W) (hF : ContinuousOn F W) {x₀ : X} (hx₀ : ∀ (y : α), (x₀, ι y) ∈ W) :
∃ (C : ℝ), ∀ᶠ (x : X) in nhds x₀, ∀ (y : α), (x, ι y) ∈ W ∧ ‖F (x, ι y)‖ ≤ C

A function continuous on an open set W ⊆ X × P is bounded on {x} × ι(α), uniformly for x near a point x₀ with {x₀} × ι(α) ⊆ W, when α is compact and ι is continuous.