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2004

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Articles 271 - 300 of 319

Full-Text Articles in Mathematics

On \Theta-Euclidean L-Fuzzy Ideals Of Rings, Ayten Koç, Erol Balkanay Jan 2004

On \Theta-Euclidean L-Fuzzy Ideals Of Rings, Ayten Koç, Erol Balkanay

Turkish Journal of Mathematics

In this paper we define a \theta-Euclidean level subset and a \theta-Euclidean level ideal. We also give some properties of a \theta-Euclidean level subset.

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A Generalization Of A Result On Torsion-Free Groups With All Subgroups Subnormal, Tahi̇re Özen Jan 2004

A Generalization Of A Result On Torsion-Free Groups With All Subgroups Subnormal, Tahi̇re Özen

Turkish Journal of Mathematics

The main result in this paper is the following: Let G be a torsion-free locally nilpotent group and let F be a finitely generated subgroup of G. If every subgroup of G containing F is subnormal in G, then G is nilpotent.

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Asymptotic And Numerical Solutions For Diffusion Models For Compounded Risk Reserves With Dividend Payments, Sally S. L. Shao, C. L. Chang Jan 2004

Asymptotic And Numerical Solutions For Diffusion Models For Compounded Risk Reserves With Dividend Payments, Sally S. L. Shao, C. L. Chang

Mathematics and Statistics Faculty Publications

We study a family of diffusion models for compounded risk reserves which account for the investment income earned and for the inflation experienced on claim amounts. We are interested in the models in which the dividend payments are paid from the risk reserves. After defining the process of conditional probability in finite time, martingale theory turns the nonlinear stochastic differential equation to a special class of boundary value problems defined by a parabolic equation with a nonsmooth coefficient of the convection term. Based on the behavior of the total income flow, asymptotic and numerical methods are used to solve the …

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Constructing Random Probability Distributions, Theodore P. Hill, David E.R. Sitton Jan 2004

Constructing Random Probability Distributions, Theodore P. Hill, David E.R. Sitton

Research Scholars in Residence

This article surveys several classes of iterative methods for constructing random probability distributions (or random convex functions, or random homeomorphisms), and includes illustrative applications in statistics, optimal-control theory, and game theory. Computer simulations of these methods are fast and easy to implement

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A Model For Radiation Interactions With Matter, Carrie Beck Jan 2004

A Model For Radiation Interactions With Matter, Carrie Beck

Senior Honors Theses and Projects

The intent of this project is to derive a realistic mathematical model for radiation interactions with matter. The model may be solved analytically, but I will also employ two computational methods, a finite difference method and a stochastic (Monte Carlo) method to gain insight into the physical process and to test the numerical techniques. Radiation interactions with matter constitute a large number of important scientific, industrial, and medical applications. This project will derive a model for the interaction of radiation with matter, which might allow one to compare different designs for shielding. It is also applicable in atmospheric physics in …

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A 2-Chain Can Interlock With A K-Chain, Julie Glass, Stefan Langerman, Joseph O'Rourke, Jack Snoeyink, Jianyuan K. Zhong Jan 2004

A 2-Chain Can Interlock With A K-Chain, Julie Glass, Stefan Langerman, Joseph O'Rourke, Jack Snoeyink, Jianyuan K. Zhong

Computer Science: Faculty Publications

One of the open problems posed in [3] is: what is the minimal number k such that an open, flexible k-chain can interlock with a flexible 2-chain? In this paper, we establish the assumption behind this problem, that there is indeed some k that achieves interlocking. We prove that a flexible 2-chain can interlock with a flexible, open 16-chain.

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Reversible Modified Reconstructability Analysis Of Boolean Circuits And Its Quantum Computation, Anas Al-Rabadi, Martin Zwick Jan 2004

Reversible Modified Reconstructability Analysis Of Boolean Circuits And Its Quantum Computation, Anas Al-Rabadi, Martin Zwick

Complex Systems Faculty Publications and Presentations

Modified Reconstructability Analysis (MRA) can be realized reversibly by utilizing Boolean reversible (3,3) logic gates that are universal in two arguments. The quantum computation of the reversible MRA circuits is also introduced. The reversible MRA transformations are given a quantum form by using the normal matrix representation of such gates. The MRA-based quantum decomposition may play an important role in the synthesis of logic structures using future technologies that consume less power and occupy less space.

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Modified Reconstructability Analysis For Many-Valued Functions And Relations, Anas Al-Rabadi, Martin Zwick Jan 2004

Modified Reconstructability Analysis For Many-Valued Functions And Relations, Anas Al-Rabadi, Martin Zwick

Complex Systems Faculty Publications and Presentations

A novel many-valued decomposition within the framework of lossless Reconstructability Analysis is presented. In previous work, Modified Recontructability Analysis (MRA) was applied to Boolean functions, where it was shown that most Boolean functions not decomposable using conventional Reconstructability Analysis (CRA) are decomposable using MRA. Also, it was previously shown that whenever decomposition exists in both MRA and CRA, MRA yields simpler or equal complexity decompositions. In this paper, MRA is extended to many-valued logic functions, and logic structures that correspond to such decomposition are developed. It is shown that many-valued MRA can decompose many-valued functions when CRA fails to do …

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Uniqueness Theorems In Bioluminescence Tomography, Ge Wang, Yi Li, Ming Jiang Jan 2004

Uniqueness Theorems In Bioluminescence Tomography, Ge Wang, Yi Li, Ming Jiang

Mathematics and Statistics Faculty Publications

Motivated by bioluminescent imaging needs for studies on gene therapy and other applications in the mouse models, a bioluminescence tomography (BLT) system is being developed in the University of Iowa. While the forward imaging model is described by the well-known diffusion equation, the inverse problem is to recover an internal bioluminescent source distribution subject to Cauchy data. Our primary goal in this paper is to establish the solution uniqueness for BLT under practical constraints despite the ill-posedness of the inverse problem in the general case. After a review on the inverse source literature, we demonstrate that in the general case …

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A Combintorial Proof Of The Sum Of Q-Cubes, Kristina Garrett, Kristin Hummel Jan 2004

A Combintorial Proof Of The Sum Of Q-Cubes, Kristina Garrett, Kristin Hummel

Mathematics and Statistics Faculty Work

We give a combinatorial proof of a q-analogue of the classical formula for the sum of cubes.

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The Dual Spectral Set Conjecture, Steen Pedersen Jan 2004

The Dual Spectral Set Conjecture, Steen Pedersen

Mathematics and Statistics Faculty Publications

Suppose that Λ = (aZ + b) ∪ (cZ + d) where a, b, c, d are real numbers such that a ≠ 0 and c ≠ 0. The union is not assumed to be disjoint. It is shown that the translates Ω + λ, λ is an element of Λ, tile the real line for some bounded measurable set Ω if and only if the exponentials eλ(x) = ei2πλx, λ is an element of Λ, form an orthogonal basis for some bounded measurable set Ω'.

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Zeros Of Functions With Finite Dirichlet Integral, William T. Ross, Stefan Richter, Carl Sundberg Jan 2004

Zeros Of Functions With Finite Dirichlet Integral, William T. Ross, Stefan Richter, Carl Sundberg

Department of Math & Statistics Faculty Publications

In this paper, we refine a result of Nagel, Rudin, and Shapiro (1982) concerning the zeros of holomorphic functions on the unit disk with finite Dirichlet integral.

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The Backward Shift On The Space Of Chauchy Transforms, William T. Ross, Joseph A. Cima, Alec L. Matheson Jan 2004

The Backward Shift On The Space Of Chauchy Transforms, William T. Ross, Joseph A. Cima, Alec L. Matheson

Department of Math & Statistics Faculty Publications

This note examines the subspaces of the space of Cauchy transforms of measures on the unit circle that are invariant under the backward shift operator f --> z-1 (f—f (0)). We examine this question when the space of Cauchy transforms is endowed with both the norm and weak* topologies.

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Reliability Estimation Based On System Data With An Unknown Load Share Rule, Hyoungtae Kim, Paul H. Kvam Jan 2004

Reliability Estimation Based On System Data With An Unknown Load Share Rule, Hyoungtae Kim, Paul H. Kvam

Department of Math & Statistics Faculty Publications

We consider a multicomponent load-sharing system in which the failure rate of a given component depends on the set of working components at any given time. Such systems can arise in software reliability models and in multivariate failure-time models in biostatistics, for example. A load-share rule dictates how stress or load is redistributed to the surviving components after a component fails within the system. In this paper, we assume the load share rule is unknown and derive methods for statistical inference on load-share parameters based on maximum likelihood. Components with (individual) constant failure rates are observed in two environments: (1) …

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A Nonlinear Random Coefficients Model For Degradation Testing, Suk Joo Bae, Paul H. Kvam Jan 2004

A Nonlinear Random Coefficients Model For Degradation Testing, Suk Joo Bae, Paul H. Kvam

Department of Math & Statistics Faculty Publications

As an alternative to traditional life testing, degradation tests can be effective in assessing product reliability when measurements of degradation leading to failure can be observed. This article presents a degradation model for highly reliable light displays, such as plasma display panels and vacuum fluorescent displays (VFDs). Standard degradation models fail to capture the burn-in characteristics of VFDs, when emitted light actually increases up to a certain point in time before it decreases (or degrades) continuously. Random coefficients are used to model this phenomenon in a nonlinear way, which allows for a nonmonotonic degradation path. In many situations, the relative …

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Tree-Like Continua And 2-To-1 Maps, Jo Heath, Van C. Nall Jan 2004

Tree-Like Continua And 2-To-1 Maps, Jo Heath, Van C. Nall

Department of Math & Statistics Faculty Publications

It is not known if there is a 2-to-1 map from a continuum onto a tree-like continuum. In fact, it is not known if there is a 2-to-1 map onto a hereditarily decomposable tree-like continuum. We show that the domain of such a map would have to contain an indecomposable continuum.

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Prolongations And Cyclic Vectors, William T. Ross, Harold S. Shapiro Jan 2004

Prolongations And Cyclic Vectors, William T. Ross, Harold S. Shapiro

Department of Math & Statistics Faculty Publications

For functions belonging to invariant subspaces of the backward shift operator Bf = (f − f(0))/z on spaces of analytic functions on the unit disk D, we explore, in a systematic way, the continuation properties of these functions.

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Common Cyclic Vectors For Normal Operators, William T. Ross, Warren R. Wogen Jan 2004

Common Cyclic Vectors For Normal Operators, William T. Ross, Warren R. Wogen

Department of Math & Statistics Faculty Publications

If μis a finite compactly supported measure on C, then the set Sμ of multiplication operators Mᵩ : L2 (μ) --> L2 (μ), Mᵩ f = ᵩ f, where ᵩ ϵ L ∞ (μ) is injective on a set of full μ measure, is the complete set of cyclic multiplication operators on L2 (μ) In this paper, we explore the question as to whether or not Sμ has a common cyclic vector

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Computational Geometry Column 45, Joseph O'Rourke Jan 2004

Computational Geometry Column 45, Joseph O'Rourke

Computer Science: Faculty Publications

The algorithm of Edelsbrunner for surface reconstruction by "wrapping" a set of points in R3 is described.

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The Theory Of Jacobi Systems And Their Abelian Representations, M. Shahryari, Y. Zamani Jan 2004

The Theory Of Jacobi Systems And Their Abelian Representations, M. Shahryari, Y. Zamani

Turkish Journal of Mathematics

In this article we introduce a new generalization of the concept of Lie ring which we call Jacobi system and we investigate some elementary properties of these systems and their Abelian representations.

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On The Power Subgroups Of The Extended Modular Group \Gamma, Recep Şahi̇n, Sebahatti̇n İki̇kardeş, Özden Koruoğlu Jan 2004

On The Power Subgroups Of The Extended Modular Group \Gamma, Recep Şahi̇n, Sebahatti̇n İki̇kardeş, Özden Koruoğlu

Turkish Journal of Mathematics

In this paper we describe the group structure of power subgroups \Gamma^m of the extended modular group \Gamma and the quotients to them. Then we give some relations between the power subgroups \Gamma^m, the commutator subgroups \Gamma^{\prime} and \Gamma^{\prime \prime} and also the information of interest about free normal subgroups of the extended modular group \Gamma.

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New Special Curves And Developable Surfaces, Shyuichi Izumiya, Nobuko Takeuchi Jan 2004

New Special Curves And Developable Surfaces, Shyuichi Izumiya, Nobuko Takeuchi

Turkish Journal of Mathematics

We define new special curves in Euclidean 3-space which we call slant helices and conical geodesic curves. Those notions are generalizations of the notion of cylindrical helices. One of the results in this paper gives a classification of special developable surfaces under the condition of the existence of such a special curve as a geodesic. As a result, we consider geometric invariants of space curves. By using these invariants, we can estimate the order of contact with those special curves for general space curves. All arguments in this paper are straight forward and classical. However, there have been no papers …

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Groups With Rank Restrictions On Non-Subnormal Subgroups, Leonid Andreevich Kurdachenko, Howard Smith Jan 2004

Groups With Rank Restrictions On Non-Subnormal Subgroups, Leonid Andreevich Kurdachenko, Howard Smith

Turkish Journal of Mathematics

Let G be a group in which every non-subnormal subgroup has finite rank. This paper considers the question as to which extra conditions on such a group G ensure that G has all subgroups subnormal. For example, if G is torsion-free and locally soluble-by-finite then either G has finite 0-rank or G is nilpotent. Several results are obtained on soluble (respectively, locally soluble-by-finite) groups satisfying the stated hypothesis on subgroups.

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Modules Supplemented Relative To A Torsion Theory, M. Tamer Koşan, Abdullah Harmanci Jan 2004

Modules Supplemented Relative To A Torsion Theory, M. Tamer Koşan, Abdullah Harmanci

Turkish Journal of Mathematics

This article introduces the concept of a \tau-supplemented module as follows: Given a hereditary torsion theory in Mod R with associated torsion functor \tau, we say that a module M is \tau-supplemented when for every submodule N of M there exists a direct summand K of M such that K\leq N and N/K is \tau-torsion module. We present here some fundamental properties of this class of modules and study the decompositions of \tau-supplemented modules under certain conditions on modules. The question of which direct sum of \tau-supplemented R-modules are \tau-supplemented is treated here.

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On Orthogonal Generalized Derivations Of Semiprime Rings, Nurcan Argaç, Atsushi Nakajima, Emi̇ne Albaş Jan 2004

On Orthogonal Generalized Derivations Of Semiprime Rings, Nurcan Argaç, Atsushi Nakajima, Emi̇ne Albaş

Turkish Journal of Mathematics

In this paper, we present some results concerning two generalized derivations on a semiprime ring. These results are a generalization of results of M. Bre\u{s}ar and J. Vukman in [2], which are related to a theorem of E. Posner for the product of derivations on a prime ring.

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On Near-Rings With Two-Sided \Alpha-Derivations, Nurcan Argaç Jan 2004

On Near-Rings With Two-Sided \Alpha-Derivations, Nurcan Argaç

Turkish Journal of Mathematics

In this paper, we introduce the notion of two-sided \alpha-derivation of a near-ring and give some generalizations of [1]. Let N be a near ring. An additive mapping f: N\rightarrow N is called an { \it (\alpha, \beta)-derivation } if there exist functions \alpha,\beta : N\rightarrow N such that f(xy)=f(x)\alpha(y)+\beta (x)f(y) for all x,y\in N. An additive mapping d:N\rightarrow N is called a two-sided \alpha-derivation if d is an (\alpha,1)-derivation as well as a (1,\alpha)-derivation. The purpose of this paper is to prove the following two assertions: (i) Let N be a semiprime near-ring, I be a subset of N …

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Ideal Theory In Topological Algebras, A. Najmi Jan 2004

Ideal Theory In Topological Algebras, A. Najmi

Turkish Journal of Mathematics

Given a simplicial topologically non radical algebra A, we characterize its topological radical, radA. If furthermore A is advertive, then radA coincides with the Jacobson radical RadA. On the other hand, it is shown that every two-sided invertive simplicial topological Gelfand-Mazur algebra has a functional spectrum and for every topologically nonradical simplicial Gelfand-Mazur amits the set \mathcal{X}(A), of all continuous multiplicative linear functionals, is not empty.

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Coisotropic Submanifolds Of A Semi-Riemannian Manifold, Erol Kiliç, Bayram Şahi̇n, H. B. Karadağ, R. Güneş Jan 2004

Coisotropic Submanifolds Of A Semi-Riemannian Manifold, Erol Kiliç, Bayram Şahi̇n, H. B. Karadağ, R. Güneş

Turkish Journal of Mathematics

In this paper, we study coisotropic submanifolds of a semi-Riemannian manifold. We investigate the integrability condition of the screen distribution and give a necessary and sufficient condition on Ricci tensor of a coisotropic submanifold to be symmetric. Finally, we present some new theorems and results about totally umbilical coisotropic submanifolds of a semi-Riemannian manifold

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On Simultaneous Approximation By A Linear Combination Of A New Sequence Of Linear Positive Operators, P. N. Agrawal, Ali J. Mohammad Jan 2004

On Simultaneous Approximation By A Linear Combination Of A New Sequence Of Linear Positive Operators, P. N. Agrawal, Ali J. Mohammad

Turkish Journal of Mathematics

In [1] we introduced a new sequence of linear positive operators M_{n} to approximate unbounded continuous functions of exponential growth on [0,\infty). As this sequence is saturated with O(n^{-1}), to accelerate the rate of convergence we applied the technique of linear combination introduced by May [3] and Rathore et al. [4] to these operators. The object of the present paper is to study the phenomena of simultaneous approximation (approximation of derivatives of functions by the corresponding order derivatives of operators) by the linear combination M_{n} ( . , k, x) of M_{n}. First, we establish a Voronovskaja-type asymptotic formula and …

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F-Invariant Submanifolds Of Kaehlerian Product Manifold, Mehmet Atçeken Jan 2004

F-Invariant Submanifolds Of Kaehlerian Product Manifold, Mehmet Atçeken

Turkish Journal of Mathematics

In this paper, the geometry of F-invariant submanifolds of a Kaehlerian product manifold is studied. The fundamental properties of these submanifolds are investigated such as pseudo umbilical, curvature invariant, totally geodesic, mixed geodesic submanifold and locally decomposable Riemannian product manifold.

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