English
The family of closed entourages forms a basis of the uniformity: HasBasis (𝓤 α) (fun V : Set (α × α) => V ∈ 𝓤 α) closure.
Русский
Семейство замкнутых энтурджей образует базис униформности: HasBasis (𝓤 α) (fun V : Set (α × α) => V ∈ 𝓤 α) closure.
LaTeX
$$$HasBasis (\\mathcal{U} α) (\\lambda V : \\mathrm{Set}(α \\times α) \\Rightarrow V \\in \\mathcal{U} α) \\mathrm{closure}$$$
Lean4
/-- Closed entourages form a basis of the uniformity filter. -/
theorem uniformity_hasBasis_closure : HasBasis (𝓤 α) (fun V : Set (α × α) => V ∈ 𝓤 α) closure :=
(𝓤 α).basis_sets.uniformity_closure