English
There is a canonical ring isomorphism from R to End_R(R)^{op} given by left multiplication: r ↦ (x ↦ r x).
Русский
Существует канонический кольцевой изоморфизм R ≅ End_R(R)^{op}, заданный левым умножением: r ↦ (x ↦ r x).
LaTeX
$$$R \\cong \\mathrm{End}_R(R)^{\\mathrm{op}},\\; r \\mapsto (x \\mapsto r x).$$$
Lean4
/-- The canonical (semi)ring isomorphism from `R` to `Module.End Rᵐᵒᵖ R` induced by the left
multiplication. -/
@[simps]
def moduleEndSelfOp : R ≃+* Module.End Rᵐᵒᵖ R :=
{ Module.toModuleEnd _ _ with
toFun := DistribMulAction.toLinearMap _ _
invFun := fun f ↦ f 1
left_inv := mul_one
right_inv := fun _ ↦ LinearMap.ext_ring_op <| mul_one _ }