English

The p-rank $\epsilon$-conjecture on class groups is true for towers of p-extensions

Number Theory 2022-08-08 v2

Abstract

Let p\ge2 be a given prime number. We prove, for any number field kappa and any integer e\ge1, the p-rank ϵ\epsilon-conjecture, on the p-class groups Cl\_F, for the family F\_kappa^p^e of towers F/kappa built as successive degree p cyclic extensions (without any other Galois conditions) such that F/kappa be of degree p^e, namely: #(Cl\_F[p])<<\_{kappa,p^e,ϵ\epsilon}(\sqrtD\_F)^ϵ\epsilon, where D\_F is the absolute value of the discriminant (Theorem 3.6) and, more generally, #(Cl\_F[p^r])<<\_{kappa,p^e,ϵ\epsilon}(\sqrtD\_F)^ϵ\epsilon, for any r\ge1 fixed. This Note generalizes the case of the family F\_Q^p (Genus theory and ϵ\epsilon-conjectures on p-class groups, J. Number Theory 207, 423--459 (2020)), whose techniques appear to be "universal" for all relative degree p cyclic extensions and use the Montgomery--Vaughan result on prime numbers. Then we prove, for F\_kappa^p^e, the p-rank ϵ\epsilon-conjecture on the cohomology groups H^2(G\_F,Z\_p) of Galois p-ramification theory over F (Theorem 4.3) and for some other classical finite p-invariants of F, as the Hilbert kernels and the logarithmic class groups.

Keywords

Cite

@article{arxiv.2001.07500,
  title  = {The p-rank $\epsilon$-conjecture on class groups is true for towers of p-extensions},
  author = {Georges Gras},
  journal= {arXiv preprint arXiv:2001.07500},
  year   = {2022}
}

Comments

Important improvements giving more general families of fields, whence a modification of the title; 15 pages. Generalize: https://doi.org/10.1016/j.jnt.2019.07.008