We study the level of nonformally real function fields of surfaces over number fields and show that it is at most 4 for a large class of surfaces.  2002 Elsevier Science (USA) The level of a field F is the least integer n such that -1 is expressible as a sum of n squares in F. If -1 is not a sum o
On Class Number Relations over Function Fields
β Scribed by Julie T.-Y Wang; Jing Yu
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 263 KB
- Volume
- 69
- Category
- Article
- ISSN
- 0022-314X
No coin nor oath required. For personal study only.
β¦ Synopsis
The analogues of the classical Kronecker and Hurwitz class number relations for function fields of any positive characteristic are obtained by a method parallel to the classical proof. In the case of even characteristic, purely inseparable orders also have to be taken into account. A subtle point is the inseparability of the j-invariants for these orders.
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We list all imaginary cyclotomic extensions β«ήβ¬ x, β³ rβ«ήβ¬ x with ideal class q M Ε½ x . q number equal to one. Apart from the zero genus ones, there are 17 solutions up to Ε½ . β«ήβ¬ x -isomorphism: 13 of them are defined over β«ήβ¬ and the 4 remainings are q 3 defined over β«ήβ¬ .
For a prime number p, let β«ήβ¬ p be the finite field of cardinality p and X Ο X p a fixed indeterminate. We prove that for any natural number N, there exist infinitely many pairs ( p, K/β«ήβ¬ p (X )) of a prime number p and a ''real'' quadratic extension K/β«ήβ¬ p (X ) for which the genus of K is one and
In a previous paper we proved that there are 11 quadratic algebraic function fields with divisor class number two. Here we complete the classification of algebraic function fields with divisor class number two giving all non-quadratic solutions. Our result is the following. Let us denote by k the fi