English

The ramification tree and almost Dedekind domains of prescribed SP-rank

Commutative Algebra 2024-05-08 v1

Abstract

Given a valuation vv with quotient field KK and a sequence K:K0K1\mathcal{K} :K_0\subseteq K_1\subseteq\cdots of finite extensions of KK, we construct a weighted tree T(v,K)\mathcal{T}(v,\mathcal{K}) encoding information about the ramification of vv in the extensions KiK_i; conversely, we show that a weighted tree T\mathcal{T} can be expressed as T(v,K)\mathcal{T}(v,\mathcal{K}) under some mild hypothesis on vv or on T\mathcal{T}. We use this construction to construct, for every countable successor ordinal number α\alpha, an almost Dedekind domain DD, integral over VV (the valuation domain of vv) whose SP-rank is α\alpha. Subsequently, we extend this result to countable limit ordinal numbers by considering integral extensions of Dedekind domains with countably many maximal ideals.

Keywords

Cite

@article{arxiv.2405.04523,
  title  = {The ramification tree and almost Dedekind domains of prescribed SP-rank},
  author = {Balint Rago and Dario Spirito},
  journal= {arXiv preprint arXiv:2405.04523},
  year   = {2024}
}