English
If a function is differentiable-on-closure on a ball, then it is continuous on the closed ball.
Русский
Если функция непрерывна на замкнутом шаре, то она непрерывна на замкнутом шаре.
LaTeX
$$$$\\text{If } DiffContOnCl\\ f\\ (ball\\ x\\ r)\\text{ holds, then } ContinuousOn\\ f\\ (closedBall\\ x\\ r). $$$$
Lean4
protected theorem mono (h : DiffContOnCl 𝕜 f s) (ht : t ⊆ s) : DiffContOnCl 𝕜 f t :=
⟨h.differentiableOn.mono ht, h.continuousOn.mono (closure_mono ht)⟩