Prime Producing Quadratic Polynomials and Class Number One or Two

Let d≡ 5 mod 8 be a positive square-free integer and let h(d) be the class number of the real quadratic field ℚ(√d). Let p be a divisor of d = pq and let . Assume that is prime or equal to 1 for all integers x with 0≤x<W. Under the assumption that the Riemann hypothesis is true, we prove that if , then h(d) < 2. Furthermore we show that h(d)< 2 implies d < 4245. In the case when there exists at least one split prime less than W, we prove the following results without any assumptions on the Riemann hypothesis. If then h< 2 or h = 4. If , then h≤ 2, h = 4 or h = 2^t−2, where t is the number of primes dividing d. In the case when h = 2^t−2 we have , where φ = 2 or 4. 2000 Mathematics Subject Classification: Primary–11R29     

实二次域Q(P(1/2))(p≡3(mod 4))类数的上界

设p是适合p≡3（Pod4）的奇素数,h,ε分别是实二次域Q的类数和基本单位．本文运用初等方法证明了：εh＜（p a 2)a 2/4(a 2)!,其中     

Ideal class groups and their subgroups of real quadratic fields

A necessary and sufficient condition is given for the ideal class group H(m) of a real quadratic field Q (√m) to contain a cyclic subgroup of ordern. Some criteria satisfying the condition are also obtained. And eight types of such fields are proved to have this property, e.g. fields withm=(z ⁿ +t−1)²+4t(witht|z ⁿ −1), which contains the well-known fields withm=4z ⁿ +1 andm=4z ²ⁿ +4 as special cases. Project supported by the National Natural Science Foundation of China.     

Universal octonary diagonal forms over some real quadratic fields

In this paper, we will prove there are infinitely many integers n such that n ²— 1 is square-free and admits universal octonary diagonal quadratic forms. Received: November 2, 1998.     

Universal forms over $\mathbb{Q}(\sqrt{5})$

In this paper, we find all quaternary universal positive definite integral quadratic forms over and prove an analogue of Conway and Schneeberger’s 15-Theorem. This work was partially supported by KRF(2003-070-C00001). This work was supported by the Brain Korea 21 project in 2004.     

On the history of the study of ideal class groups

This is a survey of a series of results about the class groups of algebraic number fields, with particular emphasis on two articles of Chebotarev [Eine Verallgemeinerung des Minkowski'schen Satzes mit Anwendung auf die Betrachtung der Körperidealklassen, Berichte der wissenschaftlichen Forschungsinstitute in Odessa 1(4) (1924) 17–20; Zur Gruppentheorie des Klassenkörpers, J. Reine Angew. Math. 161 (1929/30) 179–193; corrigendum, ibid. 164 (1931) 196] which seem to be almost forgotten. Their relationship to earlier work on the one hand, and to selected subsequent contributions on the other hand, is discussed. In this way, there emerges an interesting line of development, up to the present day, of results due to Kummer, Hasse, Leopoldt, Iwasawa, and others. More recent work treated here includes results by Cornell and Rosen (1981) and Lemmermeyer (2003) describing the structure of the class group under quite general conditions.     

Some Lambert Series Expansions of Products of Theta Functions

Let q be a complex number satisfying |q| < 1. The theta function (q) is defined by (q) = . Ramanujan has given a number of Lambert series expansions such as

The prime at infinity and the rank of the class group in global function fields

In this paper we construct, for any integers m and n, and 2?g?m-1, infinitely many function fields K of degree m over F(T) such that the prime at infinity splits into exactly g primes in K and the ideal class group of K contains a subgroup isomorphic to (Z/nZ)^m-g. This extends previous results of the author and Lee for the cases g=1 and g=m.     

Abelian subgroups of any order in class groups of global function fields

Let be a finite field with q elements, and T a transcendental element over . In this paper, we construct infinitely many real function fields of any fixed degree over with ideal class numbers divisible by any given positive integer greater than 1. For imaginary function fields, we obtain a stronger result which shows that for any relatively prime integers m and n with m,n>1 and relatively prime to the characteristic of , there are infinitely many imaginary fields of fixed degree m such that the class group contains a subgroup isomorphic to .     

关于Q(4k~(2n)+1)的理想类群的循环子群

设ｄ,ａ,ｋ,ｎ是适合４ｋ２ｎ＋１＝ｄａ２,ｋ＞１,ｎ＞２,ｄ无平方因子的正整数;又设Ｃ（Ｋ）和ｈ（Ｋ）分别是实二次域Ｋ的理想类群和类数．本文证明了：当ａ＜０．５ｋ０．５６ｎ时,则ｈ（ｋ）＝０（ｍｏｄｎ）和Ｃ（Ｋ）必有ｎ阶循环子群．