English
The map of a monoid into its skew monoid algebra is given by a ↦ single a 1; this is a monoid homomorphism with multiplication reflecting the skew product.
Русский
Вложение моноида в skew-монойдную алгебру задаётся как a ↦ single a 1 и является гомоморфизмом по умножению, отражающим skew-правило произведения.
LaTeX
$$$\mathrm{of} : G \to \mathrm{SkewMonoidAlgebra}(k,G),\quad \mathrm{of}(a) = \mathrm{single}(a,1)$$$
Lean4
/-- `single 1` as a `RingHom` -/
def singleOneRingHom : k →+* SkewMonoidAlgebra k G
where
__ := singleAddHom 1
map_one' := rfl
map_mul' x
y := by
simp [ZeroHom.toFun_eq_coe, AddMonoidHom.toZeroHom_coe, singleAddHom_apply, single_mul_single, mul_one, one_smul]