English
For an invertible module M over R, the canonical map from R to End_R(M) given by scalar multiplication is a bijection.
Русский
Для обратимого модуля M над R каноническое отображение R в End_R(M), заданное умножением на скаляры, является биекцией.
LaTeX
$$$\operatorname{toModuleEnd}_R(M): R \to \operatorname{End}_R(M) \text{ is bijective}$$$
Lean4
theorem toModuleEnd_bijective : Function.Bijective (toModuleEnd R (S := R) M) :=
by
have :
toModuleEnd R (S := R) M =
(lid R M).conj ∘
rTensorEquiv R R (comm .. ≪≫ₗ linearEquiv R M) ∘ RingEquiv.moduleEndSelf R ∘ MulOpposite.opEquiv :=
by ext; simp [LinearEquiv.conj, liftAux]
simpa [this] using MulOpposite.opEquiv.bijective