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Mathlib.Analysis.Normed.Group.ZeroAtInfty

ZeroAtInftyContinuousMapClass in normed additive groups #

In this file we give a characterization of the predicate zero_at_infty from ZeroAtInftyContinuousMapClass. A continuous map f is zero at infinity if and only if for every ε > 0 there exists a r : ℝ such that for all x : E with r < ‖x‖ it holds that ‖f x‖ < ε.

theorem ZeroAtInftyContinuousMapClass.norm_le {E : Type u_1} {F : Type u_2} {𝓕 : Type u_3} [SeminormedAddGroup E] [SeminormedAddCommGroup F] [FunLike 𝓕 E F] [ZeroAtInftyContinuousMapClass 𝓕 E F] (f : 𝓕) (ε : ) (hε : 0 < ε) :
∃ (r : ), ∀ (x : E), r < xf x < ε
theorem zero_at_infty_of_norm_le {E : Type u_1} {F : Type u_2} [SeminormedAddGroup E] [SeminormedAddCommGroup F] [ProperSpace E] (f : EF) (h : ∀ (ε : ), 0 < ε∃ (r : ), ∀ (x : E), r < xf x < ε) :