scholarly journals On Unit Groups of Absolute Abelian Number Fields of Degree pq

1960 ◽  
Vol 16 ◽  
pp. 73-81
Author(s):  
Hideo Yokoi
Keyword(s):  
Abelian Group ◽  
Number Field ◽  
Unit Group ◽  
Number Fields ◽  
Free Subgroup ◽  
Finite Degree ◽  
Maximal Torsion ◽  
Torsion Free Subgroup ◽  
Torsion Free ◽  
Arbitrary Abelian Group

In this note, we denote by Q the rational number field, by EΩ the whole unit group of an arbitrary number field Ω of finite degree, and by rΩ the rank of where generally G* for an arbitrary abelian group G means a maximal torsion-free subgroup of G. (NK/ΩEK)* is shortly denoted by and (G1 : G2) is, as usual, the index of a subgroup G2 in G1.

scholarly journals Kummer Theory for Number Fields and the Reductions of Algebraic Numbers II

2020 ◽  
Vol 15 (1) ◽  
pp. 75-92 ◽  
Author(s):  
Antonella Perucca ◽  
Pietro Sgobba
Keyword(s):  
Rational Number ◽  
Prime Power ◽  
Number Fields ◽  
Free Subgroup ◽  
Algebraic Numbers ◽  
Kummer Theory ◽  
Adic Valuation ◽  
Torsion Free Subgroup ◽  
Almost All ◽  
Torsion Free

AbstractLet K be a number field, and let G be a finitely generated and torsion-free subgroup of K×. For almost all primes p of K, we consider the order of the cyclic group (G mod 𝔭), and ask whether this number lies in a given arithmetic progression. We prove that the density of primes for which the condition holds is, under some general assumptions, a computable rational number which is strictly positive. We have also discovered the following equidistribution property: if ℓe is a prime power and a is a multiple of ℓ (and a is a multiple of 4 if ℓ =2), then the density of primes 𝔭 of K such that the order of (G mod 𝔭) is congruent to a modulo ℓe only depends on a through its ℓ-adic valuation.

scholarly journals Leopoldt kernels and central extensions of algebraic number fields

1990 ◽  
Vol 120 ◽  
pp. 67-76 ◽  
Author(s):  
Katsuya Miyake
Keyword(s):  
Number Field ◽  
Algebraic Number ◽  
Unit Group ◽  
Algebraic Number Field ◽  
Number Fields ◽  
Prime Divisors ◽  
Finite Degree ◽  
Algebraic Number Fields ◽  
Central Extensions ◽  
The Real

Let k be an algebraic number field of finite degree, and p be a fixed rational prime. We denote the set of all the non-Archimedian prime divisors of k by S0(k) and the set of all the real Archimedian ones by (k). Put and S = S0 ∪ S∞, and define a subgroup of the unit group (k) of k by

scholarly journals Kummer theory for number fields and the reductions of algebraic numbers

2019 ◽  
Vol 15 (08) ◽  
pp. 1617-1633 ◽  
Author(s):  
Antonella Perucca ◽  
Pietro Sgobba
Keyword(s):  
Number Field ◽  
Arithmetic Progression ◽  
Direct Proof ◽  
Number Fields ◽  
Algebraic Numbers ◽  
Kummer Theory ◽  
Multiplicative Order ◽  
Higher Rank ◽  
Multiplicative Subgroup ◽  
Torsion Free

For all number fields the failure of maximality for the Kummer extensions is bounded in a very strong sense. We give a direct proof (without relying on the Bashmakov–Ribet method) of the fact that if [Formula: see text] is a finitely generated and torsion-free multiplicative subgroup of a number field [Formula: see text] having rank [Formula: see text], then the ratio between [Formula: see text] and the Kummer degree [Formula: see text] is bounded independently of [Formula: see text]. We then apply this result to generalize to higher rank a theorem of Ziegler from 2006 about the multiplicative order of the reductions of algebraic integers (the multiplicative order must be in a given arithmetic progression, and an additional Frobenius condition may be considered).

scholarly journals Unit Groups of Cyclic Extensions

1957 ◽  
Vol 12 ◽  
pp. 221-229 ◽  
Author(s):  
Tomio Kubota
Keyword(s):  
Prime Number ◽  
Number Field ◽  
Algebraic Number ◽  
Unit Group ◽  
Algebraic Number Field ◽  
Cyclic Extension ◽  
Finite Degree ◽  
Norm Group

Let Ω be an algebraic number field of finite degree, which we fix once for all, and let K be a cyclic extension over Ω such that the degree of K/Ω is a powerof a prime number l. It is obvious that the norm group NK/ΩeK of the unit group ek of K, being a subgroup of the unit group e of Ω contains the groupconsisting of all-th powersof ε∈e.

The Symplectic Representation and the Torelli Group

2017 ◽  
Author(s):  
Benson Farb ◽  
Dan Margalit
Keyword(s):  
Finite Index ◽  
Algebraic Structure ◽  
Symplectic Form ◽  
Intersection Number ◽  
Free Subgroup ◽  
Torelli Group ◽  
Residually Finite ◽  
Basic Properties ◽  
Torsion Free Subgroup ◽  
Torsion Free

This chapter discusses the basic properties and applications of a symplectic representation, denoted by Ψ‎, and its kernel, called the Torelli group. After describing the algebraic intersection number as a symplectic form, the chapter presents three different proofs of the surjectivity of Ψ‎, each illustrating a different theme. It also illustrates the usefulness of the symplectic representation by two applications to understanding the algebraic structure of Mod(S). First, the chapter explains how this representation is used by Serre to prove the theorem that Mod(Sɡ) has a torsion-free subgroup of finite index. It thens uses the symplectic representation to prove, following Ivanov, the following theorem of Grossman: Mod(Sɡ) is residually finite. It also considers some of the pioneering work of Dennis Johnson on the Torelli group. In particular, a Johnson homomorphism is constructed and some of its applications are given.

scholarly journals Hypertypes of torsion-free abelian groups of finite rank

1989 ◽  
Vol 39 (1) ◽  
pp. 21-24 ◽  
Author(s):  
H.P. Goeters ◽  
C. Vinsonhaler ◽  
W. Wickless
Keyword(s):  
Abelian Group ◽  
Finite Rank ◽  
Free Abelian Group ◽  
Abelian Groups ◽  
Free Subgroup ◽  
Torsion Free Abelian Group ◽  
Free Abelian Groups ◽  
Torsion Free

Let G be a torsion-free abelian group of finite rank n and let F be a full free subgroup of G. Then G/F is isomorphic to T1 ⊕ … ⊕ Tn, where T1 ⊆ T2 ⊆ … ⊆ Tn ⊆ ℚ/ℤ. It is well known that type T1 = inner type G and type Tn = outer type G. In this note we give two characterisations of type Ti for 1 < i < n.

A REDUCTION TO THE COMPACT CASE FOR GROUPS DEFINABLE IN O-MINIMAL STRUCTURES

2014 ◽  
Vol 79 (01) ◽  
pp. 45-53
Author(s):  
ANNALISA CONVERSANO
Keyword(s):  
Lie Groups ◽  
Compact Subgroup ◽  
Free Subgroup ◽  
Homotopy Equivalent ◽  
Minimal Structure ◽  
Compact Case ◽  
Torsion Free Subgroup ◽  
Image Position ◽  
Torsion Free

Abstract Let ${\cal N}\left( G \right)$ be the maximal normal definable torsion-free subgroup of a group G definable in an o-minimal structure M. We prove that the quotient $G/{\cal N}\left( G \right)$ has a maximal definably compact subgroup K, which is definably connected and unique up to conjugation. Moreover, we show that K has a definable torsion-free complement, i.e., there is a definable torsion-free subgroup H such that $G/{\cal N}\left( G \right) = K \cdot H$ and $K\mathop \cap \nolimits^ \,H = \left\{ e \right\}$ . It follows that G is definably homeomorphic to $K \times {M^s}$ (with $s = {\rm{dim}}\,G - {\rm{dim}}\,K$ ), and homotopy equivalent to K. This gives a (definably) topological reduction to the compact case, in analogy with Lie groups.

scholarly journals On the Absolute Ideal Class Groups of Relatively Meta-Cyclic Number Fields of a Certain Type

1960 ◽  
Vol 17 ◽  
pp. 171-179 ◽  
Author(s):  
Taira Honda
Keyword(s):  
Number Field ◽  
Algebraic Number Field ◽  
Number Fields ◽  
Ideal Class ◽  
Class Groups ◽  
Finite Degree ◽  
Ground Field ◽  
Root Of Unity ◽  
Ideal Class Groups ◽  
A Finite Group

Notations. The following notations will be used throughout this paper.˛: the identity of a finite group.Q: the rational number field.P: an algebraic number field of finite degree, fixed as the ground field.l: a prime number.ζl: a primitive l-th root of unity.

scholarly journals Subexponential class group and unit group computation in large degree number fields

2014 ◽  
Vol 17 (A) ◽  
pp. 385-403 ◽  
Author(s):  
Jean-François Biasse ◽  
Claus Fieker
Keyword(s):  
Number Field ◽  
Riemann Hypothesis ◽  
Class Group ◽  
Large Degree ◽  
Unit Group ◽  
Number Fields ◽  
Ideal Class ◽  
Ideal Class Group ◽  
Subexponential Class ◽  
The Ideal

AbstractWe describe how to compute the ideal class group and the unit group of an order in a number field in subexponential time. Our method relies on the generalized Riemann hypothesis and other usual heuristics concerning the smoothness of ideals. It applies to arbitrary classes of number fields, including those for which the degree goes to infinity.

Sign in / Sign up

Export Citation Format

Share Document