English
If injectivity holds for all FG submodules, then it holds for any submodule M'.
Русский
Если инъективность верна для всех FG-подмодулей, то она верна и для любого подмодуля M'.
LaTeX
$$$(\\forall M' : Submodule R M, M'.FG) \\Rightarrow Injective(rTensor N M'.subtype) \\Rightarrow Injective(rTensor N M'.subtype)$$
Lean4
/-- If the map $M' \otimes N \to M \otimes N$ is injective for every finitely generated submodule
$M' \subseteq M$, then it is in fact injective for every submodule $M' \subseteq M$. -/
theorem rTensor_injective_of_forall_fg_rTensor_injective
(hMN : ∀ (M' : Submodule R M) (_ : M'.FG), Injective (rTensor N M'.subtype)) (M' : Submodule R M) :
Injective (rTensor N M'.subtype) :=
(forall_vanishesTrivially_iff_forall_rTensor_injective R).mp
((forall_vanishesTrivially_iff_forall_fg_rTensor_injective R).mpr hMN) M'