A note on integer-valued skew polynomials
Abstract
Given an integral domain D with quotient field K, the study of the ring of integer-valued polynomials Int(D)={f∈K[X]|f(a)∈Dfor alla∈D} has attracted a lot of attention over the past decades. Recently, Werner has extended this study to the situation of skew polynomials. To be more precise, if σ is an automorphism of K, one may consider the set Int(D,σ)={f∈K[X,σ]|f(a)∈Dfor alla∈D}, where K[X,σ] is the skew polynomial ring and f(a) is a “suitable” evaluation of f at a. For example, he gave sufficient conditions for Int(D,σ) to be a ring and study some of its properties. In this paper, we extend the study to the situation of the skew polynomial ring K[X,σ,δ] with a suitable evaluation, where δ is a σ-derivation. Moreover we prove, for example, that if σ is of finite order and D is a Dedekind domain with finite residue fields such that Int(D,σ) is a ring, then Int(D,σ) is non-Noetherian.
Communicated by André Leroy