English
IsVonNBounded(s − t) iff s = ∅ or t = ∅ or both s,t are vonNBounded.
Русский
IsVonNBounded(s − t) эквивалентно (s = ∅) или (t = ∅) или обоим s,t ограничены фон Нейманом.
LaTeX
$$$\\operatorname{IsVonNBounded}_{\\mathbb{k}}(s - t) \\iff (s = \\emptyset) \\lor (t = \\emptyset) \\lor (\\operatorname{IsVonNBounded}_{\\mathbb{k}}(s) \\land \\operatorname{IsVonNBounded}_{\\mathbb{k}}(t)).$$$
Lean4
theorem isVonNBounded_ball (r : ℝ) : Bornology.IsVonNBounded 𝕜 (Metric.ball (0 : E) r) :=
isVonNBounded_of_isBounded _ Metric.isBounded_ball