For an extension of local fields, a scaffold is shown to be a powerful tool for dealing with the problem of the freeness of fractional ideals over their associated orders (Byott, Childs and Elder: \textit{Scaffolds and Generalized Integral Galois Module Structure}, Ann. Inst. Fourier, 2018). The first class of field extensions admitting scaffolds is \enquote*{near one-dimensional elementary abelian extension}, introduced by Elder (\textit{Galois Scaffolding in One-dimensional Elementary Abelian Extensions}, Proc. Amer. Math. Soc. 2009). However, the scaffolds constructed in Elder's paper arise only from the classical Hopf-Galois structure. Therefore, the study in this thesis aims to investigate scaffolds in non-classical Hopf-Galois structures. Let $L/K$ be a near one-dimensional elementary abelian extension of degree $p^2$ for a prime $p \geq 3.$ We show that, among the $p^2-1$ non-classical Hopf-Galois structures on the extension, there are only $p-1$ of them for which scaffolds may exist, and these exist only under certain restrictive arithmetic condition on the ramification break numbers for the extension. The existence of scaffolds is beneficial for determining the freeness status of fractional ideals of $\mathfrak{O}_L$ over their associated orders. In almost all other cases, there is no fractional ideal which is free over its associated order. As a result, scaffolds fail to exist.

No description available.

Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

In this dissertation we investigate prior definitions for p-adic continued fractions and introduce some new definitions. We introduce a continued fraction algorithm for quadratic irrationals, prove periodicity for Q₂ and Q₃, and numerically observe periodicity for Q(p) when p < 37. Various observations and calculations regarding this algorithm are discussed, including a new type of symmetry observed in many of these periods, which is different from the palindromic symmetry observed for real continued fractions and some previously defined p-adic continued fractions. Other results are proved for p-adic continued fractions of various forms. Sufficient criteria are given for a class of p-adic continued fractions of rational numbers to be finite. An algorithm is given which results in a periodic continued fraction of period length one for √D ∈ Zˣ(p), D ∈ Z, D non-square; although, different D require different parameters to be used in the algorithm. And, a connection is made between continued fractions and de Weger’s approximation lattices, so that periodic continued fractions can be generated from a periodic sequence of approximation lattices, for square roots in Zˣ(p). For simple p-adic continued fractions with rational coefficients, we discuss observations and calculations related to Browkin’s continued fraction algorithms. In the last chapter, we apply some of the definitions and techniques developed in the earlier chapters for Q(p) and Z to the t-adic function field case F(q)((t)) and F(q)[t], respectively. We introduce a continued fraction algorithm for quadratic irrationals in F(q)((t)) that always produces periodic continued fractions.

No description available.

In the thesis, we propose a newly-developed method called the method of Connected Local Fields (CLF) to analyze opto-electromagnetic passive devices. The method of CLF somewhat resembles a hybrid between the finite difference and pseudo-spectral methods. For opto-electromagnetic passive devices, our primary concern is their steady state behavior, or narrow-band characteristics, so we use a frequency-domain method, in which the system is governed by the Helmholtz equation. The essence of CLF is to use the intrinsic general solution of the Helmholtz equation to expand the local fields on the compact stencil. The original equation can then be transformed into the discretized form called LFE-9 (in 2-D case), and the intrinsic reconstruction formulae describing each overlapping local region can be obtained. Further, we present rigorous analysis of the numerical dispersion equation of LFE-9, by means of first-order approximation, and acquire the closed-form formula of the relative numerical dispersion error. We are thereby able to grasp the tangible influences brought both by the sampling density as well as the propagation direction of plane wave on dispersion error. In our dispersion analysis, we find that the LFE-9 formulation achieves the sixth-order accuracy: the theoretical highest order for discretizing elliptic partial differential equations on a compact nine-point stencil. Additionally, the relative dispersion error of LFE-9 is less than 1%, given that sampling density greater than 2.1 points per wavelength. At this point, the sampling density is nearing that of the Nyquist-Shannon sampling limit, and therefore computational efforts can be significantly reduced.

Thesis (MSc (Mathematics))--Stellenbosch University, 2008. / This is an exposition of the explicit approach to Local Class Field Theory due to J. Tate and J. Lubin. We mainly follow the treatment given in [15] and [25]. We start with an informal introduction to p-adic numbers. We then review the standard theory of valued elds and completion of those elds. The complete discrete valued elds with nite residue eld known as local elds are our main focus. Number theoretical aspects for local elds are considered. The standard facts about Hensel's lemma, Galois and rami cation theory for local elds are treated. This being done, we continue our discussion by introducing the key notion of relative Lubin-Tate formal groups and modules. The torsion part of a relative Lubin-Tate module is then used to generate a tower of totally rami ed abelian extensions of a local eld. Composing this tower with the maximal unrami ed extension gives the maximal abelian extension: this is the local Kronecker-Weber theorem. What remains then is to state and prove the theorems for explicit local class eld theory and end our discussion.

The field of discrete dynamical systems is a rich and active field of research within mathematics, with applications ranging from biology to computer science, finance, engineering and various others. In this thesis properties of certain discrete dynamical systems are studied together with number theoretic properties of the functions defining these systems. The dynamical systems studied in this thesis are defined by iteration of power series g with a fixed point at the origin, tangent to the identity, and defined over fields of prime characteristic p. We are interested in the geometric location of the periodic points in the open unit disk. Recent results have shown that there is a connection between the lower ramification numbers of g and the geometric location of the periodic points in the open unit disk. The lower ramification numbers of g can be described as the multiplicity of zero as a fixed point of p-power iterates of g. Part of this thesis concerns characterizing power series having certain sequences of ramification numbers. The other part concerns utilizing these results in order to describe the geometric location of the periodic points in terms of their distance to the origin. More precisely, we characterize all 2-ramified power series, i.e. power series having ramification numbers of the form 2(1 + p + … + pn). Moreover, we also obtain a lower bound of the absolute value of the periodic points in the open unit disk of such series.

Cette thèse est consacrée à l'étude des déformations des C*-algèbres munies d'une action de groupe, du point de vue de la quantification équivariante non-formelle, dans le cas non-archimédien. Nous construisons une théorie de déformation des C*-algèbres munies d'une action d'un espace vectoriel de dimension finie sur un corps local non-archimédien de caractéristique différente de 2 ainsi que pour des quotients du groupe affine d'un corps local dont le corps résiduel est de cardinal impair. Par ailleurs, nous construisons des familles de 2-cocycles unitaires afin de déformer des groupes quantiques localement compacts agissant sur ces C*-algèbres déformées. / This thesis is devoted to the study of deformation of C*-algebras endowed with a group action, from the perspective of non-formal equivariant quantization, in the non-Archimedean setting. We construct a deformation theory of C*-algebras endowed with an action of a finite dimensional vector space over a non-Archimedean local field of characteristic different from 2 and for quotients of the affine group of a local field whose residue field has cardinality not divisible by 2. Moreover, we construct families of dual unitary 2-cocycles in order to deform locally compact quantum groups acting on these deformed C*-algebras.

Für eine Primzahl p, sei L eine endliche Erweiterung von $QQ_p$ mit Ganzheitsring $O_L$ und Restklassenk\"{o}rper $kk_L$. Sei ferner n eine positive ganze Zahl. In dieser Arbeit beschreiben wir die Kategorie der endlich erzeugten stetigen Darstellungen der n-ten direkten Potenz der absoluten Galoisgruppe $G_L$ von L mit Koeffizienten in $O_L$, unter Verwendung einer verallgemeinerten Version der $(phi, Gamma)$-Moduln von Fontaine. In Kapitel 4 beweisen wir, dass die Kategorie der stetigen Darstellungen der n-ten direkten Potenz von $G_L$ auf endlichen dimensionalen $kk_L$-Vektorräumen und die Kategorie étaler $(phi, Gamma)$-Moduln über einem n-variablen Laurentreihenring über $kk_L$ äquivalent sind. In Kapitel 5 erweitern wir diese Äquivalenz, um zu beweisen, dass die Kategorie der stetigen Darstellungen der n-ten direkten Potenz von $G_L$ auf endlich erzeugten $O_L$-Moduln und die Kategorie étaler $(phi, Gamma)$-Moduln über einem n-variablen Laurentreihenring über $O_L$ äquivalent sind. Einerseits erhalten wir, wenn wir n=1 und L willkürlich lassen, die Verfeinerung von Fontaine ursprünglicher Konstruktion gemäß Kisin, Rin und Schneider, die Lubin-Tate Theorie verwenden. Wenn wir andererseits n willkürlich lassen und $L=QQ_p$, erhalten wir die Theorie von Zábrádi von multivariablen zyklotomischen $(phi, Gamma)$-Moduln, die Fontaines Verwendung einer einzelnen freien Variablen verallgemeinert. Daher bietet unsere Arbeit einen gemeinsamen Rahmen für diese beiden Verallgemeinerungen. / For a prime number p, let L be a finite extension of $QQ_p$ with ring of integers $O_L$ and residue field $kk_L$. We also let n be a positive integer. In this thesis we describe the category of finitely generated continuous representations of the n-th direct power of the absolute Galois group $G_L$ of L with coefficients in $O_L$ using a generalized version of Fontaine's $(phi, Gamma)$-modules. In Chapter 4 we prove that the category of continuous representations of the n-th direct power of $G_L$ on finite dimensional $kk_L$-vector spaces is equivalent to the category of étale $(phi, Gamma)$-modules over a n-variable Laurent series ring over $kk_L$. In Chapter 5 we extend this equivalence to prove that the category of continuous representations of the n-th direct power of $G_L$ on finitely generated $O_L$-modules is equivalent to the category of étale $(phi, Gamma)$-modules over a n-variable Laurent series ring over $O_L$. On the one hand, if we let n=1 and $L$ be arbitrary, we obtain the refinement of Fontaine's original construction due to Kisin, Rin and Schneider, which uses Lubin-Tate theory. On the other hand, if we let n be arbitrary and $L=QQ_p$, we recover Zábrádi's theory of multivariable cyclotomic $(phi,Gamma)$-modules that generalizes Fontaine's use of a single free variable. Therefore, our thesis provides a common framework for both of these generalizations.