Ascending chain conditions on principal left and right ideals for semidirect products of semigroups

Abstract

In this paper we investigate the ascending chain conditions on principal left and right ideals for semidirect products of semigroups and show how this is connected to the corresponding problem for rings of skew generalized power series. Let S be a left cancellative semigroup with a unique idempotent e, T a right cancellative semigroup with an idempotent f and \(\omega: T \to \operatorname {End}(S)\) a semigroup homomorphism such that ω(f)=idS. We show that in this case the semidirect product S⋊ωT satisfies the ascending chain condition for principal left ideals (resp. right ideals) if and only if S and T satisfy the ascending chain condition for principal left ideals (resp. right ideals and \(\operatorname {Im}\omega(t)\) is closed for complete inverses for all t∈T). We also give several examples to show that for more general semigroups these implications may not hold.