English
Let R be an integral domain and x ∈ R with x ≠ 0. The map I ↦ (span {x}) · I from ideals to ideals is injective.
Русский
Пусть R — целостный домен, x ∈ R, x ≠ 0. Отображение I ↦ (span {x}) · I от идеалов в идеалы инъективно.
LaTeX
$$$\\text{Let }R\\text{ be an integral domain and }x\\in R\\text{ with }x\\neq 0.\\ For\\ all\\ ideals\\ I,J\\subseteq R,\\ (\\operatorname{span}\\{x\\})I=(\\operatorname{span}\\{x\\})J\\ \\Rightarrow\\ I=J.$$$
Lean4
theorem span_singleton_mul_right_injective [IsDomain R] {x : R} (hx : x ≠ 0) :
Function.Injective ((span { x } : Ideal R) * ·) := fun _ _ => (span_singleton_mul_right_inj hx).mp