English
The linear topologies on R and on Rᵐᵒᵖ R are characterized by a basis of neighborhoods of zero formed by two-sided ideals.
Русский
Линейные топологии на R и на Rᵐᵒᵖ R задаются базой окрестностей нуля, сформированной двусторонними идеалами.
LaTeX
$$$ IsLinearTopology R R \\wedge IsLinearTopology R^{op} R \\iff (\\mathcal{N}0).HasBasis (fun I : TwoSidedIdeal R \\mapsto (I:Set R) \\in 𝓝 0) (fun I => I:Set R) $$$
Lean4
theorem _root_.isLinearTopology_iff_hasBasis_twoSidedIdeal :
IsLinearTopology R R ∧ IsLinearTopology Rᵐᵒᵖ R ↔
(𝓝 0).HasBasis (fun I : TwoSidedIdeal R ↦ (I : Set R) ∈ 𝓝 0) (fun I : TwoSidedIdeal R ↦ (I : Set R)) :=
⟨fun ⟨_, _⟩ ↦ hasBasis_twoSidedIdeal, fun h ↦
⟨.mk_of_hasBasis' R h fun I r x hx ↦ I.mul_mem_left r x hx,
.mk_of_hasBasis' Rᵐᵒᵖ h fun I r x hx ↦ I.mul_mem_right x r.unop hx⟩⟩