English
For modules that are localized, their rank remains invariant under base change to the localized ring.
Русский
Для локализованных модулей их ранг сохраняется при базовом переходе к локализации.
LaTeX
$$$\\operatorname{rank}_{R_S}(M_S) = \\operatorname{rank}_R(M).$$$
Lean4
/-- Let `N₁ N₂ : Submodule R M`. If the localization of `N₁` at each maximal ideal `P` is equal to
the localization of `N₂` at `P`, then `N₁ = N₂`. -/
theorem eq_of_localization₀_maximal {N₁ N₂ : Submodule R M}
(h : ∀ (P : Ideal R) [P.IsMaximal], N₁.localized₀ P.primeCompl (f P) = N₂.localized₀ P.primeCompl (f P)) :
N₁ = N₂ :=
le_antisymm (Submodule.le_of_localization_maximal Mₚ f fun P _ ↦ (h P).le)
(Submodule.le_of_localization_maximal Mₚ f fun P _ ↦ (h P).ge)