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  Partner: UNT Libraries
 Department: Department of Mathematics
 Language: English
 Collection: UNT Theses and Dissertations
A Collapsing Result Using the Axiom of Determinancy and the Theory of Possible Cofinalities

A Collapsing Result Using the Axiom of Determinancy and the Theory of Possible Cofinalities

Date: May 2001
Creator: May, Russell J.
Description: Assuming the axiom of determinacy, we give a new proof of the strong partition relation on ω1. Further, we present a streamlined proof that J<λ+(a) (the ideal of sets which force cof Π α < λ) is generated from J<λ+(a) by adding a singleton. Combining these results with a polarized partition relation on ω1
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Natural Smooth Measures on the Leaves of the Unstable Manifold of Open Billiard Dynamical Systems

Natural Smooth Measures on the Leaves of the Unstable Manifold of Open Billiard Dynamical Systems

Date: December 1998
Creator: Richardson, Peter A. (Peter Adolph), 1955-
Description: In this paper, we prove, for a certain class of open billiard dynamical systems, the existence of a family of smooth probability measures on the leaves of the dynamical system's unstable manifold. These measures describe the conditional asymptotic behavior of forward trajectories of the system. Furthermore, properties of these families are proven which are germane to the PYC programme for these systems. Strong sufficient conditions for the uniqueness of such families are given which depend upon geometric properties of the system's phase space. In particular, these results hold for a fairly nonrestrictive class of triangular configurations of scatterers.
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Existence of Many Sign Changing Non Radial Solutions for Semilinear Elliptic Problems on Annular Domains

Existence of Many Sign Changing Non Radial Solutions for Semilinear Elliptic Problems on Annular Domains

Date: August 1998
Creator: Finan, Marcel Basil
Description: The aim of this work is the study of the existence and multiplicity of sign changing nonradial solutions to elliptic boundary value problems on annular domains.
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Polish Spaces and Analytic Sets

Polish Spaces and Analytic Sets

Date: August 1997
Creator: Muller, Kimberly (Kimberly Orisja)
Description: A Polish space is a separable topological space that can be metrized by means of a complete metric. A subset A of a Polish space X is analytic if there is a Polish space Z and a continuous function f : Z —> X such that f(Z)= A. After proving that each uncountable Polish space contains a non-Borel analytic subset we conclude that there exists a universally measurable non-Borel set.
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Traveling Wave Solutions of the Porous Medium Equation

Traveling Wave Solutions of the Porous Medium Equation

Date: May 2013
Creator: Paudel, Laxmi P.
Description: We prove the existence of a one-parameter family of solutions of the porous medium equation, a nonlinear heat equation. In our work, with space dimension 3, the interface is a half line whose end point advances at constant speed. We prove, by using maximum principle, that the solutions are stable under a suitable class of perturbations. We discuss the relevance of our solutions, when restricted to two dimensions, to gravity driven flows of thin films. Here we extend the results of J. Iaia and S. Betelu in the paper "Solutions of the porous medium equation with degenerate interfaces" to a higher dimension.
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Graev Metrics and Isometry Groups of Polish Ultrametric Spaces

Graev Metrics and Isometry Groups of Polish Ultrametric Spaces

Date: May 2013
Creator: Shi, Xiaohui
Description: This dissertation presents results about computations of Graev metrics on free groups and characterizes isometry groups of countable noncompact Heine-Borel Polish ultrametric spaces. In Chapter 2, computations of Graev metrics are performed on free groups. One of the related results answers an open question of Van Den Dries and Gao. In Chapter 3, isometry groups of countable noncompact Heine-Borel Polish ultrametric spaces are characterized. The notion of generalized tree is defined and a correspondence between the isomorphism group of a generalized tree and the isometry group of a Heine-Borel Polish ultrametric space is established. The concept of a weak inverse limit is introduced to capture the characterization of isomorphism groups of generalized trees. In Chapter 4, partial results of isometry groups of uncountable compact ultrametric spaces are given. It turns out that every compact ultrametric space has a unique countable orbital decomposition. An orbital space consists of disjoint orbits. An orbit subspace of an orbital space is actually a compact homogeneous ultrametric subspace.
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Algebraically Determined Rings of Functions

Algebraically Determined Rings of Functions

Date: August 2010
Creator: McLinden, Alexander Patrick
Description: Let R be any of the following rings: the smooth functions on R^2n with the Poisson bracket, the Hamiltonian vector fields on a symplectic manifold, the Lie algebra of smooth complex vector fields on C, or a variety of rings of functions (real or complex valued) over 2nd countable spaces. Then if H is any other Polish ring and &#966;:H &#8594;R is an algebraic isomorphism, then it is also a topological isomorphism (i.e. a homeomorphism). Moreover, many such isomorphisms between function rings induce a homeomorphism of the underlying spaces. It is also shown that there is no topology in which the ring of real analytic functions on R is a Polish ring.
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Dimensions in random constructions.

Dimensions in random constructions.

Date: May 2002
Creator: Berlinkov, Artemi
Description: We consider random fractals generated by random recursive constructions, prove zero-one laws concerning their dimensions and find their packing and Minkowski dimensions. Also we investigate the packing measure in corresponding dimension. For a class of random distribution functions we prove that their packing and Hausdorff dimensions coincide.
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Understanding Ancient Math Through Kepler: A Few Geometric Ideas from The Harmony of the World

Understanding Ancient Math Through Kepler: A Few Geometric Ideas from The Harmony of the World

Date: August 2002
Creator: Arthur, Christopher
Description: Euclid's geometry is well-known for its theorems concerning triangles and circles. Less popular are the contents of the tenth book, in which geometry is a means to study quantity in general. Commensurability and rational quantities are first principles, and from them are derived at least eight species of irrationals. A recently republished work by Johannes Kepler contains examples using polygons to illustrate these species. In addition, figures having these quantities in their construction form solid shapes (polyhedra) having origins though Platonic philosophy and Archimedean works. Kepler gives two additional polyhedra, and a simple means for constructing the “divine” proportion is given.
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On the Cohomology of the Complement of a Toral Arrangement

On the Cohomology of the Complement of a Toral Arrangement

Date: August 1999
Creator: Sawyer, Cameron Cunningham
Description: The dissertation uses a number of mathematical formula including de Rham cohomology with complex coefficients to state and prove extension of Brieskorn's Lemma theorem.
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