English
For any property P of ring homomorphisms, having the localization-span property is equivalent to having the localization-span-finite property.
Русский
Для любой характеристики P гомоморфизмов колец локализация-области имеет эквивалентность между свойствами Span и FiniteSpan.
LaTeX
$$$\\forall P,\\; \\RingHom.OfLocalizationSpan P \\;\\Leftrightarrow \\RingHom.OfLocalizationFiniteSpan P$$$
Lean4
theorem ofLocalizationSpan_iff_finite : RingHom.OfLocalizationSpan @P ↔ RingHom.OfLocalizationFiniteSpan @P :=
by
delta RingHom.OfLocalizationSpan RingHom.OfLocalizationFiniteSpan
apply forall₅_congr
intros
constructor
· intro h s; exact h s
· intro h s hs hs'
obtain ⟨s', h₁, h₂⟩ := (Ideal.span_eq_top_iff_finite s).mp hs
exact h s' h₂ fun x => hs' ⟨_, h₁ x.prop⟩