English

Polynomial Dedekind domains with finite residue fields of prime characteristic

Commutative Algebra 2023-07-26 v3 Number Theory

Abstract

We show that every Dedekind domain RR lying between the polynomial rings Z[X]\mathbb Z[X] and Q[X]\mathbb Q[X] with the property that its residue fields of prime characteristic are finite fields is equal to a generalized ring of integer-valued polynomials, that is, for each prime pZp\in\mathbb Z there exists a finite subset EpE_p of transcendental elements over Q\mathbb Q in the absolute integral closure Zp\overline{\mathbb Z_p} of the ring of pp-adic integers such that R={fQ[X]f(Ep)Zp, prime pZ}R=\{f\in\mathbb Q[X]\mid f(E_p)\subseteq \overline{\mathbb Z_p}, \forall \text{ prime }p\in\mathbb Z\}. Moreover, we prove that the class group of RR is isomorphic to a direct sum of a countable family of finitely generated abelian groups. Conversely, any group of this kind is the class group of a Dedekind domain RR between Z[X]\mathbb Z[X] and Q[X]\mathbb Q[X].

Keywords

Cite

@article{arxiv.2207.04280,
  title  = {Polynomial Dedekind domains with finite residue fields of prime characteristic},
  author = {Giulio Peruginelli},
  journal= {arXiv preprint arXiv:2207.04280},
  year   = {2023}
}

Comments

to appear in the Pacific Journal of Math. (2023)