English
The function z ↦ |z|^2 is proper: it tends to infinity along the cocompact filter on ℂ.
Русский
Функция z ↦ |z|^2 является proper: вдоль фильтра cocompact ℂ значения стремятся к бесконечности.
LaTeX
$$$$ \\operatorname{Tendsto}(\\operatorname{normSq})\\bigl(\\operatorname{cocompact}(\\mathbb{C})\\bigr)\\operatorname{atTop}. $$$$
Lean4
/-- The `normSq` function on `ℂ` is proper. -/
theorem tendsto_normSq_cocompact_atTop : Tendsto normSq (cocompact ℂ) atTop := by
simpa [norm_mul_self_eq_normSq] using
tendsto_norm_cocompact_atTop.atTop_mul_atTop₀ (tendsto_norm_cocompact_atTop (E := ℂ))