English
For each fixed index d, the coefficient map f ↦ f.d is uniformly continuous on Laurent series with respect to the uniform structure; this holds for any base K.
Русский
Для фиксированного коэффициента d отображение f ↦ f_d равно по униформной топологии непрерывности на рядах Лаурента.
LaTeX
$$$\text{UniformContinuous}(\lambda f. f_{d})$$$
Lean4
theorem coeff_tendsto {ℱ : Filter K⸨X⸩} (hℱ : Cauchy ℱ) (D : ℤ) :
Tendsto (fun f : K⸨X⸩ ↦ f.coeff D) ℱ (𝓟 {coeff hℱ D}) :=
let _ : UniformSpace K := ⊥
le_of_eq <| DiscreteUniformity.eq_pure_cauchyConst (hℱ.map (uniformContinuous_coeff D)) ▸ (principal_singleton _).symm