English
There is a natural Galois connection between the two constructions fromIdeal and asIdeal, linking ideals and two-sided ideals via these two functors.
Русский
Существует естественное сопряжение Галуа между конструкциями fromIdeal и asIdeal, устанавливающее связь между идеалами и двусторонними идеалами через эти функторы.
LaTeX
$$$\mathrm{GaloisConnection}(\mathrm{fromIdeal},\mathrm{asIdeal})$$$
Lean4
theorem gc : GaloisConnection fromIdeal (asIdeal (R := R)) := fun I J =>
⟨fun h x hx ↦ h <| mem_span_iff.2 fun _ H ↦ H hx, fun h x hx ↦
by
simp only [fromIdeal, OrderHom.coe_mk, mem_span_iff] at hx
exact hx _ h⟩