Genus fields of Kummer ℓn-cyclic extensions

We give a construction of the genus field for Kummer [Formula: see text]-cyclic extensions of rational congruence function fields, where [Formula: see text] is a prime number. First, we compute the genus field of a field contained in a cyclotomic function field, and then for the general case. This generalizes the result obtained by Peng for a Kummer [Formula: see text]-cyclic extension. Finally, we study the extension [Formula: see text], for [Formula: see text], [Formula: see text] abelian extensions of [Formula: see text].

Integral trace form of extensions of degree pq

In this work, we present the integral trace form [Formula: see text] of a cyclic extension [Formula: see text] with degree [Formula: see text], where [Formula: see text], [Formula: see text] and [Formula: see text] are distinct odd primes, the conductor of [Formula: see text] is a square free integer, and [Formula: see text] belongs to the ring of algebraic integers [Formula: see text] of [Formula: see text]. The integral trace form of [Formula: see text] allows one to calculate the packing radius of lattices constructed via the canonical (or twisted) homomorphism of submodules of [Formula: see text].

On the embedding problem of central cyclic extensions of abelian groups

In this report we find the obstruction of the embedding problem related to a central cyclic extension of an arbitrary abelian group.

Annihilators of the Ideal Class Group of a Cyclic Extension of an Imaginary Quadratic Field

The aim of this paper is to study the group of elliptic units of a cyclic extension $L$ of an imaginary quadratic field $K$ such that the degree $[L:K]$ is a power of an odd prime $p$. We construct an explicit root of the usual top generator of this group, and we use it to obtain an annihilation result of the $p$-Sylow subgroup of the ideal class group of $L$.

Stably rational surfaces over a quasi-finite field

Let $k$ be a field and $X$ a smooth, projective, stably $k$-rational surface. If $X$ is split by a cyclic extension, for instance if the field $k$ is finite or more generally quasi-finite, then the surface $X$ is $k$-rational. Bibliography: 22 titles.

Automata with cyclic move operations for picture languages

Here, we study the cyclic extensions of Sgraffito automata and of deterministic two-dimensional two-way ordered restarting automata for picture languages. Such a cyclically extended automaton can move in a single step from the last column (or row) of a picture to the first column (or row). For Sgraffito automata, we show that this cyclic extension does not increase the expressive power of the model, while for deterministic two-dimensional two-way restarting automata, the expressive power is strictly increased by allowing cyclic moves. In fact, for the latter automata, we take the number of allowed cyclic moves in any column or row as a parameter, and we show that already with a single cyclic move per column (or row) the deterministic two-dimensional extended two-way restarting automaton can be simulated. On the other hand, we show that two cyclic moves per column or row already give the same expressive power as any finite number of cyclic moves.

On the non-existence of cyclic splitting fields for division algebras

LetDbe a division algebra over its centerFof degreen. Consider the group{\mu_{Z}(D)=\mu_{n}(F)/Z(D^{\prime})}, where{\mu_{n}(F)}is the group of all then-th roots of unity in{F^{*}}, and{Z(D^{\prime})}is the center of the commutator subgroup of the group of units{D^{*}}ofD. It is shown that if{\mu_{Z}(D\otimes_{F}L)\neq 1}for someLcontaining all the primitive{n^{k}}-th roots of unity for all positive integersk, thenDis not split by any cyclic extension ofF. This criterion is employed to prove that some special classes of division algebras are not cyclically split.

New p-dimensional lattices from cyclic extensions

In this work, [Formula: see text]-dimensional point-lattices are constructed from a number field [Formula: see text], where [Formula: see text] is a cyclic extension of degree [Formula: see text], an odd unramified prime in [Formula: see text]. Families of lattices whose packing densities asymptotically approach those of [Formula: see text], [Formula: see text], are explicitly exhibited.