English
If R is a commutative semiring with star and A is a star-ring with module structure, Unitization(R, A) becomes a star-ring with star extending the components.
Русский
Если R — коммутативная полусемiring с звездой, а A — звездообразное кольцо с модулем, Unitization(R, A) становится звёздoобразным кольцом, звезда расширяет компоненты.
LaTeX
$$$\text{StarRing}(R, A, Unitization)$$$
Lean4
instance instStarRing [CommSemiring R] [StarRing R] [NonUnitalNonAssocSemiring A] [StarRing A] [Module R A]
[StarModule R A] : StarRing (Unitization R A) :=
{ Unitization.instStarAddMonoid with
star_mul := fun x y => ext (by simp [-star_mul']) (by simp [-star_mul', add_comm (star x.fst • star y.snd)]) }