For a totally real field of prime power conductor, we determine the Fitting ideal over the Galois group ring of the ideal class group and of the narrow ideal class group. 1998 Academic Press ## 1. Introduction In this paper we prove a structure result on the ideal class group and on the narrow id
CM-Fields with Cyclic Ideal Class Groups of 2-Power Orders
✍ Scribed by Stéphane Louboutin
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 298 KB
- Volume
- 67
- Category
- Article
- ISSN
- 0022-314X
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✦ Synopsis
We prove that there are only finitely many CM-fields N with cyclic ideal class groups of 2-power orders such that the complex conjugation is the square of some automorphism of N. Since their actual determination would be too difficult, we only content ourselves with the determination of the nonquadratic imaginary cyclic number fields of 2-power degrees with cyclic ideal class groups of 2-power orders. There are exactly 22 such number fields, 10 of them having class number one, 9 of them having class number two, and 3 of them having class number four. This present determination is a nice complement to the determination of all nonquadratic imaginary cyclic number fields of 2-power degrees with ideal class groups of exponents 2 completed in an earlier paper.
📜 SIMILAR VOLUMES
In this note we prove an analogue of the classical Riemann-Hurwitz formula for the minus part of the p-rank of S-ideal class groups of algebraic CM-fields. The result is an improvement of Kida's formula for the cyclotomic Z p -extension.
A method for determining the rank of the 2-class group of imaginary bicyclic biquadratic fields is described. This method is used to determine all such fields with cyclic 2-class group. We also determine the structure of the 2 -class group in several cases when it is noncyclic. 1995 Academic Press.
Let k be an imaginary quadratic number field with C k, 2 , the 2-Sylow subgroup of its ideal class group, isomorphic to ZÂ2Z\_ZÂ2Z\_ZÂ2Z. By the use of various versions of the Kuroda class number formula, we improve significantly upon our previous lower bound for |C k 1 , 2 | , the 2-class number of