English

Rigidity of valuative trees under henselization

Algebraic Geometry 2022-08-31 v2

Abstract

Let (K,v)(K,v) be a valued field and let (Kh,vh)(K^h,v^h) be the henselization determined by the choice of an extension of vv to an algebraic closure of KK. Consider an embedding v(K)Λv(K^*)\hookrightarrow\Lambda of the value group into a divisible ordered abelian group. Let T(K,Λ)T(K,\Lambda), T(Kh,Λ)T(K^h,\Lambda) be the trees formed by all Λ\Lambda-valued extensions of vv, vhv^h to the polynomial rings K[x]K[x], Kh[x]K^h[x], respectively. We show that the natural restriction mapping T(Kh,Λ)T(K,Λ)T(K^h,\Lambda)\to T(K,\Lambda) is an isomorphism of posets. As a consequence, the restriction mapping TvTvhT_v\to T_{v^h} is an isomorphism of posets too, where TvT_v, TvhT_{v^h} are the trees whose nodes are the equivalence classes of valuations on K[x]K[x], Kh[x]K^h[x] whose restriction to KK, KhK^h are equivalent to vv, vhv^h, respectively.

Keywords

Cite

@article{arxiv.2202.02042,
  title  = {Rigidity of valuative trees under henselization},
  author = {Enric Nart},
  journal= {arXiv preprint arXiv:2202.02042},
  year   = {2022}
}
R2 v1 2026-06-24T09:19:33.873Z