We discuss Lojasiewicz's beautiful proof of the division theorem for smooth functions. The standard proofs are based on the Weierstrass preparation theorem for analytic functions and use techniques from the theory of partial differential equations. Lojasiewicz's approach is more geometric and syn¬thetic. In the appendices appear new proofs of results which are required for the theorem. / Dissertation (MSc (Mathematics))--University of Pretoria, 2006. / Mathematics and Applied Mathematics / unrestricted

Recently, was developed a new theory of the Jost function, within which, it was split in two terms involving on one side, singlevalued analytic functions of the energy, and on the other, factors responsible for the existence of the branching-points. For the single-valued part of the Jost function, a procedure for the powerseries expansion around an arbitrary point on the energy plane was suggested. However, this theory lacks a rigorous proof that these parts are entire functions of the energy. It also gives an intuitive (not rigorous) derivation of the domain where they are entire. In the present study, we ll this gap by using a method derived from the method of successive approximations. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Physics / unrestricted

In this dissertation, we study morphisms of smooth complex projective varieties to the projective line with at most two singular fibres. We show that if such a morphism has at most one singular fibre, then the domain of the morphism is uniruled and the morphism admits algebraic sections. We reach the same conclusions, but with algebraic genus zero multisections instead of algebraic sections, if the morphism has at most two singular fibres and the first Chern class of the domain of the morphism is supported in a single fibre of the morphism. To achieve these result, we use action completed symplectic cohomology groups associated to compact subsets of convex symplectic domains. These groups are defined using Pardon's virtual fundamental chains package for Hamiltonian Floer cohomology. In the above setting, we show that the vanishing of these groups implies the existence of unirulings and (multi)sections.

Quantum systems in a d-dimensional Hilbert space are considered, where the phase spase is Z(d) x Z(d). An analytic representation in a cell S in the complex plane using Theta functions, is defined. The analytic functions have exactly d zeros in a cell S. The reproducing kernel plays a central role in this formalism. Wigner and Weyl functions are also studied. Quantum systems with positions in a circle S and momenta in Z are also studied. An analytic representation in a strip A in the complex plane is also defined. Coherent states on a circle are studied. The reproducing kernel is given. Wigner and Weyl functions are considered.

yes / Quantum systems with positions and momenta in Z(d) are described by the d zeros of analytic functions on a torus. The d paths of these zeros on the torus describe the time evolution of the system. A semi-analytic method for the calculation of these paths of the zeros is discussed. Detailed analysis of the paths for periodic systems is presented. A periodic system which has the displacement operator to a real power t, as time evolution operator, is studied. Several numerical examples, which elucidate these ideas, are presented.

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A functional Analytic method which was first introduced by Larsen and Habetler for the one-speed isotropic case in 1973 is applied to full and half-space multigroup problems in one dimension with a constant and invertible transfer matrix. The Case-type eigenfunction expansion formulas for the solutions of these problems are explicitly obtained. For the half-space case, the formulas are expressed in terms of two matrices X and Y which provide the Wiener-Hopf factorization of the dispersion matrix. The method applied yields compact results avoiding the calculation of adjoint solutions and normalization integrals to determine the expansion coefficients. Since the method proves to be amenable to further generalization, the case of a degenerate transfer kernel is also considered along the same lines, yielding the expansion formulas for that problem in the full and half-space cases. The expansion formulas are shown to be valid at least for subcritical media, but an extension to critical problems is expected. / Doctor of Philosophy

Esta dissertação trata do Princípio da similaridade para as soluções das equações da forma L\'OMEGA\' = A(z) ·\'OMEGA\' + B(z) · \'BARRA\' \'omega\' , sendo L um campo vetorial complexo não singular e A,B \'PERTENCE\' \'C POT. sigma\' (\'R POT. 2\'), com 0 < \'sigma\' < 1. Aqui são apresentados resultados para o campo vetorial elítico L = \'PARTIAL SUP\' \'\'PARTIAL\' z e para classes de campos vetoriais elíticos degenerados / This dissertation deals with the Similarity principle for solutions of equations of the form L \'omega\' = A(z) · \'omega\' + B(z) · \' BARRA\' \'omega\' where L is a nonsingular complex vector field and A,B \'IT BELONGS\' \'C POT. sigma \' (\'R POT. 2\'), with 0 < \'sigma\' < 1. Here are presented results for elliptic vector field and for classes of degenerate elliptic vector fields

Esta dissertação trata do Princípio da similaridade para as soluções das equações da forma L\'OMEGA\' = A(z) ·\'OMEGA\' + B(z) · \'BARRA\' \'omega\' , sendo L um campo vetorial complexo não singular e A,B \'PERTENCE\' \'C POT. sigma\' (\'R POT. 2\'), com 0 < \'sigma\' < 1. Aqui são apresentados resultados para o campo vetorial elítico L = \'PARTIAL SUP\' \'\'PARTIAL\' z e para classes de campos vetoriais elíticos degenerados / This dissertation deals with the Similarity principle for solutions of equations of the form L \'omega\' = A(z) · \'omega\' + B(z) · \' BARRA\' \'omega\' where L is a nonsingular complex vector field and A,B \'IT BELONGS\' \'C POT. sigma \' (\'R POT. 2\'), with 0 < \'sigma\' < 1. Here are presented results for elliptic vector field and for classes of degenerate elliptic vector fields

We construct a co-analytic filter on the set of finite sequences of natural numbers, which allows us to obtain a strongly affine function of arbitrary Borel class from compact convex subset of locally convex space through single limit process (by this filter) applied to countable system of affine continuous functions. Conversely we show that function obtainted as result of such process is necessarily Borel and strongly affine. Further we generalize this method using metrizable reduction approach for Baire functions on non-metrizable spaces. Last chapter covers similar result for bi-analytic functions on separable metrizable spaces.