English
If f has compact support, then for every v ∈ E, the function x ↦ fderiv 𝕜 f x applied to v has compact support as a function of x.
Русский
Если у f компактная опора, то для любого вектора v опирается функция x ↦ fderiv 𝕜 f x acting на v с компактной опорой.
LaTeX
$$$\text{HasCompactSupport } f \Rightarrow \forall v, \text{HasCompactSupport } (\lambda x, (fderiv 𝕜 f x) \cdot v)$$$
Lean4
protected theorem fderiv (hf : HasCompactSupport f) : HasCompactSupport (fderiv 𝕜 f) :=
hf.mono' <| support_fderiv_subset 𝕜