English
The reciprocal of the neighborhood basis at 0 from the left equals atBot; i.e., inv nhdsLT 0 = atBot.
Русский
Обратное основание окрестности нуля слева равно atBot.
LaTeX
$$$(\mathcal{N}_{<0}(0))^{-1} = \mathrm{atBot}$$$
Lean4
@[simp]
theorem inv_atBot₀ : (atBot : Filter 𝕜)⁻¹ = 𝓝[<] 0 :=
(((atBot_basis_Iio' (0 : 𝕜)).map _).comp_surjective inv_surjective).eq_of_same_basis <|
(nhdsLT_basis _).congr (by simp) fun a ha ↦ by simp [inv_Iio₀ (inv_neg''.2 ha)]