English
For S a semiring and module structure over R, the nth coefficient is linear in the scalar: coeff n (a • φ) = a • coeff n φ.
Русский
Для S — полупрямой, и функция нормной модуля над R→S, n-й коэффициент от a • φ линейен по a: coeff n (a • φ) = a • coeff n φ.
LaTeX
$$$\operatorname{coeff}_n(a \cdot \varphi) = a \cdot \operatorname{coeff}_n(\varphi)$$$
Lean4
@[simp]
theorem coeff_smul {S : Type*} [Semiring S] [Module R S] (n : ℕ) (φ : PowerSeries S) (a : R) :
coeff n (a • φ) = a • coeff n φ :=
rfl