English

Bases for some modules of cyclotomic units

Number Theory 2026-04-08 v4

Abstract

Let Was(K)\mathbf{Was}(\mathbb{K}) denote the group of Washington's cyclotomic units of any abelian number field K\mathbb{K}. If K\mathbb{K} coincides with its genus field in the narrow sense, we give a Λ\Lambda-basis of lim_Was(K_k+)\lim\limits\_{\xleftarrow{}} \mathbf{Was}(\mathbb{K}\_k^{+}) where (K_k)_k0(\mathbb{K}\_k)\_{k \geqslant 0} denotes the cyclotomic Z_p\mathbb{Z}\_p-tower of K\mathbb{K} and Λ\Lambda denotes the Iwasawa's algebra. This results from a Z[1/2]\mathbb{Z} [1/2]-basis of Was(K)_ZZ[1/2]\mathbf{Was}(\mathbb{K}) \otimes\_{\mathbb{Z}} \mathbb{Z} [1/2] that we give under the same hypothesis.

Keywords

Cite

@article{arxiv.2407.02002,
  title  = {Bases for some modules of cyclotomic units},
  author = {Rafik Souanef},
  journal= {arXiv preprint arXiv:2407.02002},
  year   = {2026}
}
R2 v1 2026-06-28T17:26:04.594Z