English
The star operation induces a canonical algebra isomorphism between FreeAlgebra(R,X) and its opposite: FreeAlgebra(R,X) ≃ₐ[R] (FreeAlgebra(R,X))ᵐᵒᵖ.
Русский
Операция звезды задаёт каноническое алгебраическое изоморфизм между FreeAlgebra(R,X) и её противоположностью.
LaTeX
$$$\text{FreeAlgebra}(R,X) \cong_{\!\!R} (\text{FreeAlgebra}(R,X))^{\mathrm{op}}$$$
Lean4
/-- `star` as an `AlgEquiv` -/
def starHom : FreeAlgebra R X ≃ₐ[R] (FreeAlgebra R X)ᵐᵒᵖ :=
{ starRingEquiv with commutes' := fun r => by simp [star_algebraMap] }