dense_coborder — Mathlib

English

The coborder of any set is dense in the ambient space.

Русский

Граница coborder любого множества плотна в рамках пространства.

LaTeX

$$$\operatorname{Dense}(\operatorname{coborder}(s))$$$

Lean4

/-- The coborder of any set is dense -/
theorem dense_coborder {s : Set X} : Dense (coborder s) :=
  by
  rw [dense_iff_closure_eq, coborder_eq_union_closure_compl, closure_union, ← univ_subset_iff]
  refine _root_.subset_trans ?_ (union_subset_union_right _ (subset_closure))
  simp

Похожие утверждения