The densities for 3-ranks of tame kernels of cyclic cubic number fields

Let F be a cubic cyclic field with t(2)ramified primes.For a finite abelian group G,let r3(G)be the 3-rank of G.If 3 does not ramify in F,then it is proved that t-1 r3(K2O F)2t.Furthermore,if t is fixed,for any s satisfying t-1 s 2t-1,there is always a cubic cyclic field F with exactly t ramified primes such that r3(K2O F)=s.It is also proved that the densities for 3-ranks of tame kernels of cyclic cubic number fields satisfy a Cohen-Lenstra type formula d∞,r=3-r2∞k=1(1-3-k)r k=1(1-3-k)2.This suggests that the Cohen-Lenstra conjecture for ideal class groups can be extended to the tame kernels of cyclic cubic number fields.     

On Tame Kernels and Ideal Class Groups

It is well known that there is a close connection between tame kernels and ideal class groups of number fields. However, the latter is a very difficult subject in number theory. In this paper, we prove some results connecting the p^n-rank of the tame kernel of a cyclic cubic field F with the p^n-rank of the coinvariants of μp^n×CI（δE,T） under the action of the Galois group, where E = F（ζp^n ） and T is the finite set of primes of E consisting of the infinite primes and the finite primes dividing p. In particular, if F is a cyclic cubic field with only one ramified prime and p = 3, n = 2, we apply the results of the tame kernels to prove some results of the ideal class groups of E, the maximal real subfield of E and F（ζ3）.     

On Tame Kernel and Class Group in Terms of Quadratic Forms

The paper is to investigate the structure of the tame kernel K₂O_F for certain quadratic number fields F, which extends the scope of Conner and Hurrelbrink (J. Number Theory88 (2001), 263-282). We determine the 4-rank and the 8-rank of the tame kernel, the Tate kernel, and the 2-part of the class group. Our characterizations are in terms of binary quadratic forms X²+32Y,X²+64Y²,X²+2Py²,2X²+Py²,X²−2Py²,2X²−Py². The results are very useful for numerical computations.     

Some families of Mordell curves associated to cubic fields

We introduce some Mordell curves of two different natures both of which are associated to cubic fields. One set of them consists of those elliptic curves whose rational points over the rational number field are described by or closely related to cubic fields. The other is a one-parameter family of Mordell curves which gives all (cyclic) cubic twists and all quadratic twists of the Fermat curve X³+Y³+Z³=0.     

Generators and Relations for O

Tate's algorithm for computing O for rings of integers in a number field has been adapted for the computer and gives explicit generators for the group and sharp bounds on their order – the latter, together with some structural results on the p-primary part of O due to Tate and Keune, gives a proof of its structure for many number fields of small discriminants, confirming earlier conjectural results. For the first time, tame kernels of non-Galois fields are obtained.     

Bi-Quadratic Number Fields with Trivial 2-Primary Hilbert Kernels

Using results of Browkin and Schinzel one can easily determinequadratic number fields with trivial 2-primary Hilbert kernels.In the present paper we completely determine all bi-quadraticnumber fields which have trivial 2-primary Hilbert kernels.To obtain our results, we use several different tools, amongstwhich is the genus formula for the Hilbert kernel of an arbitraryrelative quadratic extension, which is of independent interest.For some cases of real bi-quadratic fields there is an ambiguityin the genus formula, so in this situation we use instead Brauerrelations between the Dedekind zeta-funtions and the Birch–Tateconjecture. 2000 Mathematics Subject Classification 11R70, 19F15.     

The Tate conjecture for powers of ordinary cubic fourfolds over finite fields

Recently, Levin proved the Tate conjecture for ordinary cubic fourfolds over finite fields. In this paper, we prove the Tate conjecture for self-products of ordinary cubic fourfolds. Our proof is based on properties of so-called polynomials of K3-type introduced by the author about 12 years ago.     

循环数域导子的一点注记

主要研究循环数域的导子公式.利用Kronecker-Weber定理及整体域的分歧理论,对于给定除子分歧个数的素数次循环扩域,明确给出了这类数域的导子公式及其个数.     

A Remark on Computing the Tame Kernel of Quadratic Imaginary Fields

In this paper, we discuss a method to compute the tame kernel of a number field. Confining ourselves to an imaginary quadratic field, we prove that is bijective when . Received October 25, 1999, Accepted February 5, 2001     

关于虚二次域Tame核计算的一个注记

本文给出了一种计算数域Tame核的方法.应用到虚二次域上,证明了当 Nv>8δD6时,(？)t／:K2S'F／K2SF→k*是双射。     

Burnside定理的推广

本文先证得了定理２．１，在这个基础上，推广了Ｂｕｒｎｓｉｄｅ的两个定理．     

利用有限域GF（2m）上的三项式构造二元循环码

循环码是一类特殊的线性码,由于循环码快速的编码和译码算法,它被广泛应用于消费电子,数据存储以及通信系统当中.在本文中,利用特征是偶数的有限域上的三项式构造出了两类二元循环码,我们不仅可以确定出这两类循环码最小距离的下界,而且这两类循环码在参数的选取上非常的灵活.