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Oscillation Of Nonlinear Neutral Delay Differential Equations Of Second-Order With Positive And Negative Coefficients, Mustafa Kemal Yildiz, Başak Karpuz, Özkan Öcalan Jan 2009

Oscillation Of Nonlinear Neutral Delay Differential Equations Of Second-Order With Positive And Negative Coefficients, Mustafa Kemal Yildiz, Başak Karpuz, Özkan Öcalan

Turkish Journal of Mathematics

Some oscillation criteria for the following second-order neutral differential equation [x(t)\pm r(t) f( x(t-\gamma))]''+p(t) g(x(t-\alpha)) -q(t) g(x(t-\beta )) = s(t) where t\geq t_0, \gamma,\alpha,\beta \in R^+ with \alpha \geq \beta, r \in C^2([t_0,\infty ), R^+) , p,q\in C([t_0,\infty ),R^+) and f,g\in C(R,R), s\in C([ t_0,\infty),R) have been obtained. Our results are not restricted with boundedness of solutions.


Some Properties Of The First Eigenvalue Of The $P(X)$-Laplacian On Riemannian Manifolds, R. A. Mashiyev, Guli̇zar Ali̇soy, Sezai̇ Ogras Jan 2009

Some Properties Of The First Eigenvalue Of The $P(X)$-Laplacian On Riemannian Manifolds, R. A. Mashiyev, Guli̇zar Ali̇soy, Sezai̇ Ogras

Turkish Journal of Mathematics

The main result of the present paper establishes a stability property of the first eigenvalue of the associated problem which deals with the $p(x)$-Laplacian on Riemannian manifolds with Dirichlet boundary condition.


Solutions For 2n^{Th} Order Lidstone Bvp On Time Scales, Erbi̇l Çeti̇n, S. Gülşan Topal Jan 2009

Solutions For 2n^{Th} Order Lidstone Bvp On Time Scales, Erbi̇l Çeti̇n, S. Gülşan Topal

Turkish Journal of Mathematics

In this paper, we prove the existence of solutions for nonlinear Lidstone boundary value problems by using the monotone method on time scale and also we show the existence of at least one positive solution if f is either superlinear or sublinear by the fixed point theorem in a Banach space.


A Perturbation Of M-Order Derivations On Banach Algebras, Yong-Soo Jung, Kyoo-Hong Park Jan 2009

A Perturbation Of M-Order Derivations On Banach Algebras, Yong-Soo Jung, Kyoo-Hong Park

Turkish Journal of Mathematics

Let \A be a unital Banach algebra and let m, 1 \leq m \leq 4, be an integer. If f: \A \to \A is an approximate m-order derivation in the sense of Hyers-Ulam-Rassias, then f: \A \to \A is an exact m-order derivation.


On Completeness Of Elementary Generalized Solutions Of A Class Of Operator-Differential Equations Of A Higher Order, Rovshan Z. Gumbataliev Jan 2009

On Completeness Of Elementary Generalized Solutions Of A Class Of Operator-Differential Equations Of A Higher Order, Rovshan Z. Gumbataliev

Turkish Journal of Mathematics

In this paper we give definition of m-fold completeness and prove a theorem on completeness of elementary generalized solution of corresponding boundary value problems at which the equation describes the process of corrosive fracture of metals in aggressive media and the principal part of the equation has multiple characteristics.


Intrinsic Equations For A Generalized Relaxed Elastic Line On An Oriented Surface In The Minkowski 3-Space E_1^3, Cumali̇ Eki̇ci̇, Ali̇ Görgülü Jan 2009

Intrinsic Equations For A Generalized Relaxed Elastic Line On An Oriented Surface In The Minkowski 3-Space E_1^3, Cumali̇ Eki̇ci̇, Ali̇ Görgülü

Turkish Journal of Mathematics

H. K. Nickerson and Gerald S. Manning [8] derived the intrinsic equations for a relaxed elastic line on an oriented surface in the Euclidean 3-dimensional space E^3. In this paper, we define a generalized relaxed elastic line and derive the intrinsic equations for a generalized of relaxed elastic line on an oriented surface in the Minkowski 3-dimensional space E_1^3 and give some applications of the result.


Cover And Contents Jan 2009

Cover And Contents

Turkish Journal of Mathematics

No abstract provided.


On \Phi-Recurrent Kenmotsu Manifolds, Uday Chand De, Ahmet Yildiz, Funda Yaliniz Jan 2009

On \Phi-Recurrent Kenmotsu Manifolds, Uday Chand De, Ahmet Yildiz, Funda Yaliniz

Turkish Journal of Mathematics

The object of this paper is to study \phi-recurrent Kenmotsu manifolds. Also three-dimensional locally \phi-recurrent Kenmotsu manifolds have been considered. Among others it is proved that a locally \phi-recurrent Kenmotsu spacetime is the Robertson-Walker spacetime. Finally we give a concrete example of a three-dimensional Kenmotsu manifold.


Stability Of An Euler-Lagrange Type Cubic Functional Equation, Abbas Najati, Fridoun Moradlou Jan 2009

Stability Of An Euler-Lagrange Type Cubic Functional Equation, Abbas Najati, Fridoun Moradlou

Turkish Journal of Mathematics

In this paper, we will find out the general solution and investigate the generalized Hyers-Ulam-Rassias stability problem for an Euler-Lagrange type cubic functional equation 2mf(x+my)+2f(mx-y)=(m^3+m)[f(x+y)+f(x-y)]+2(m^4-1)f(y) in Banach spaces and in left Banach modules over a unital Banach *-algebra for a fixed integer m with m\neq0,\pm1.


Geodesics Of The Cheeger-Gromoll Metric, Ari̇f A. Salimov, S. Kazimova Jan 2009

Geodesics Of The Cheeger-Gromoll Metric, Ari̇f A. Salimov, S. Kazimova

Turkish Journal of Mathematics

The main purpose of the paper is to investigate geodesics on the tangent bundle with respect to the Cheeger-Gromoll metric.


Modules With Unique Closure Relative To A Torsion Theory Ii, Semra Doğruöz, Abdullah Harmanci, Patrick F. Smith Jan 2009

Modules With Unique Closure Relative To A Torsion Theory Ii, Semra Doğruöz, Abdullah Harmanci, Patrick F. Smith

Turkish Journal of Mathematics

We study modules M over a general ring R such that every submodule has a unique closure with respect to a hereditary torsion theory \tau on Mod-R using the fact that the module M satisfies a certain transitivity property on \tau-closed submodules.


Local Fourier Bases And Ultramodulation Spaces, Salti Samarah, Fady Hasan Jan 2009

Local Fourier Bases And Ultramodulation Spaces, Salti Samarah, Fady Hasan

Turkish Journal of Mathematics

It was proved that local Fourier bases are unconditional bases for modulation spaces M_{p.q}^w. We prove that the local Fourier bases are unconditional bases for ultramodulation spaces M_p^{w_{\gamma}}=M_{p.p}^{w_{\gamma}}, where 0


Q-Modules, C. Jayaram, Ünsal Teki̇r Jan 2009

Q-Modules, C. Jayaram, Ünsal Teki̇r

Turkish Journal of Mathematics

In this paper we characterize Q-modules and almost Q-modules. Next we estblish some equivalent conditions for an almost Q-module to be a Q-module. Using these results, some characterizations are given for Noetherian Q-modules.


Oscillation Of Higher-Order Nonlinear Delay Differential Equations With Oscillatory Coefficients, Başak Karpuz, Özkan Öcalan, Mustafa Kemal Yildiz Jan 2009

Oscillation Of Higher-Order Nonlinear Delay Differential Equations With Oscillatory Coefficients, Başak Karpuz, Özkan Öcalan, Mustafa Kemal Yildiz

Turkish Journal of Mathematics

A criterion is established on the bounded solutions of type higher-order nonlinear neutral differential equations of type oscillatory or tending to zero at infinity [a(t) [x(t)+r(t)x(\kappa(t))]^{(n-1]' +p(t)F(x(\tau(t)))+q(t)G(x(\sigma(t)))= \phi(t), where t\geq t_0, n\geq 2, a,p are positive, r,q,\phi are allowed to alternate in sign infinitely many times, F,G are continuous functions, and \kappa,\tau,\sigma are strictly increasing unbounded continuous delay functions.


Some Properties Of Gr-Multiplication Ideals, Hani Khashan Jan 2009

Some Properties Of Gr-Multiplication Ideals, Hani Khashan

Turkish Journal of Mathematics

In this paper, we study some of the properties of gr-multiplication ideals in a graded ring R. We first characterize finitely generated gr-multiplication ideals and then give a characterization of gr-multiplication ideals by using the gr-localization of R. Finally we determine the set of gr-P-primary ideals of R when P is a gr-multiplication gr-prime ideal of R.


Integral And Homothetic Indecomposability With Applications To Irreducibility Of Polynomials, Fati̇h Koyuncu, Ferruh Özbudak Jan 2009

Integral And Homothetic Indecomposability With Applications To Irreducibility Of Polynomials, Fati̇h Koyuncu, Ferruh Özbudak

Turkish Journal of Mathematics

Being motivated by some methods for construction of homothetically indecomposable polytopes, we obtain new methods for construction of families of integrally indecomposable polytopes. As a result, we find new infinite families of absolutely irreducible multivariate polynomials over any field F. Moreover, we provide different proofs of some of the main results of Gao [2].


A Note On The Lévy Constant For Continued Fractions, Ting Zhong Jan 2009

A Note On The Lévy Constant For Continued Fractions, Ting Zhong

Turkish Journal of Mathematics

In this note, we study the lévy constant of continued fraction expansions. We show that for all x \in [0,1), the upper lévy constant of x is finite except a set with Hausdorff dimension one-half.


Existence And Uniqueness Theorem For Slant Immersions In Kenmotsu Space Forms, Pradeep Kumar Pandey, Ram Shankar Gupta Jan 2009

Existence And Uniqueness Theorem For Slant Immersions In Kenmotsu Space Forms, Pradeep Kumar Pandey, Ram Shankar Gupta

Turkish Journal of Mathematics

In this paper we have obtained a general existence as well as uniqueness theorem for slant immersions into a Kenmotsu-space form.


Trace Classes And Fixed Points For The Extended Modular Group \Overline{\Gamma}, Özden Koruoğlu, Recep Şahi̇n, Sebahatti̇n İki̇kardeş Jan 2008

Trace Classes And Fixed Points For The Extended Modular Group \Overline{\Gamma}, Özden Koruoğlu, Recep Şahi̇n, Sebahatti̇n İki̇kardeş

Turkish Journal of Mathematics

The extended modular group \overline{\Gamma}=PGL(2,\mathbb{Z}) is the group obtained by adding the reflection R(z)=1/\overline{z} to the generators of the modular group \Gamma =PSL(2, {Z}). In this paper, we find the trace classes of the extended modular group \overline{\Gamma}. Using this, we classify the elements of \overline{\Gamma}.


On The Regular Elements In Z_N, Osama Alkam, Emad Abu Osba Jan 2008

On The Regular Elements In Z_N, Osama Alkam, Emad Abu Osba

Turkish Journal of Mathematics

All rings are assumed to be finite commutative with identity element. An element a \in R is called a regular element if there exists b \in R such that a=a^2b, the element b is called a von Neumann inverse for a. A characterization is given for regular elements and their inverses in Z_n, the ring of integers modulo n. The arithmetic function V(n), which counts the regular elements in Z_n is studied. The relations between V(n) and Euler's phi-function \varphi (n) are explored.


Linear Connections On Light-Like Manifolds, Teki̇n Dereli̇, Şahi̇n Koçak, Murat Li̇moncu Jan 2008

Linear Connections On Light-Like Manifolds, Teki̇n Dereli̇, Şahi̇n Koçak, Murat Li̇moncu

Turkish Journal of Mathematics

It is well-known that a torsion-free linear connection on a light-like manifold (M,g) compatible with the degenerate metric g exists if and only if Rad(TM) is a Killing distribution. In case of existence, there is an infinitude of connections with none distinguished. We propose a method to single out connections with the help of a special set of 1-forms by the condition that the 1-forms become parallel with respect to this connection. Such sets of 1-forms could be regarded as an additional structure imposed upon the light-like manifold. We consider also connections with torsion and with non-metricity on light-like manifolds.


A Decomposition Method For Solving Unsteady Convection-Diffusion Problems, Shaher Momani Jan 2008

A Decomposition Method For Solving Unsteady Convection-Diffusion Problems, Shaher Momani

Turkish Journal of Mathematics

In this study, a decomposition method for approximating the solutions of unsteady convection-diffusion problems is implemented. The approximate solution is calculated in the form of a convergent series with easily computable components. The calculations are accelerated by using the noise terms phenomenon for nonhomogeneous problems. Numerical examples are investigated to illustrate the pertinent features of the proposed algorithm.


Mirror Principle For Flag Manifolds, Vehbi̇ Emrah Paksoy Jan 2008

Mirror Principle For Flag Manifolds, Vehbi̇ Emrah Paksoy

Turkish Journal of Mathematics

In this paper, using mirror principle developped by Lian, Liu and Yau [8, 9, 10, 11, 12, 13] we obtained the A and B series for the equivariant tangent bundles over homogenous spaces using Chern polynomial. This is necessary to obtain related cohomology valued series for given arbitrary vector bundle and multiplicative characteristic class. Moreover, this can be used as a valuable testing ground for the theories which associates quantum cohomologies and J functions of non-abelian quotient to abelian quotients via quantization.


Mixed Type Of Integral Equation With Potential Kernel, Mohamed Abdella A. Abdou, Gamal Mohamed Abd Al-Kader Jan 2008

Mixed Type Of Integral Equation With Potential Kernel, Mohamed Abdella A. Abdou, Gamal Mohamed Abd Al-Kader

Turkish Journal of Mathematics

This paper presents the solution of an integral equation of a mixed type in three-dimensions in the space L_2 (\Omega) \times C[0,T], where T < \infty, and \Omega is the domain of integration with respect to position. The kernel of position integral term is considered in the potential function form, while the kernel of time is considered as a continuous kernel. A linear system of Fredholm integral equations of the first and second kinds are obtained and solved. Krein's method is used to solve the Fredholm integral equation of the first kind, while the second kind is solved numerically.


A Note On A Problem Of J. Galambos, Lu-Ming Shen, Yue-Hua Liu, Yu-Yuan Zhou Jan 2008

A Note On A Problem Of J. Galambos, Lu-Ming Shen, Yue-Hua Liu, Yu-Yuan Zhou

Turkish Journal of Mathematics

For any x\in (0,1], letx = \frac{1}{d_1} + \frac{a_1}{b_1} \frac{1}{d_2} + ··· + \frac{a_1a_2 ··· a_n}{b_1b_2 ··· b_n} \frac{1}{d_{n+1}} + ··· be the Oppenheim series expansion of x. In this paper, we investigate the Hausdorff dimension of the set B_m={x:1


Cover For Modules And Injective Modules, N. Amiri Jan 2008

Cover For Modules And Injective Modules, N. Amiri

Turkish Journal of Mathematics

Let R be a commutative ring with identity and M be an R-module with Spec(M) \neq \phi. A cover of the R-submodule K of M is a subset C of Spec(M) satisfying that for any x \in K, x \neq 0, there is N \in C such that ann(x) \subset (N:M). If we denote by J = \bigcap_{N \in C} (N:M) and assume that M is finitely generated, then JM=M implies that M=0, M is called C-injective provided each R-homomorphism \phi : (N:M) \rightarrow M with N \in C can be lifted to an R-homomorphism \lambda : R \rightarrow M. …


On Non-Existence Of Lightlike Hypersurfaces Of Indefinite Kenmotsu Space Form, Nesi̇p Aktan Jan 2008

On Non-Existence Of Lightlike Hypersurfaces Of Indefinite Kenmotsu Space Form, Nesi̇p Aktan

Turkish Journal of Mathematics

In this paper, lightlike hypersurfaces of indefinite Kenmotsu space form are studied. Some characterizations of non-existence of lightlike hypersurfaces of indefinite Kenmotsu space form are given.


Cr-Submanifolds Of An S-Manifold, A. Alghanemi Jan 2008

Cr-Submanifolds Of An S-Manifold, A. Alghanemi

Turkish Journal of Mathematics

The study of CR-submanifolds of a Kaehler manifold was initiated by Bejancu [1]. Since then many papers have appeared on CR-submanifolds. The purpose of this paper is to studied the CR-submanifolds of an S-manifold. In particular, we studied the integrability of the distributions D and D^{\bot} of a CR-submanifold of an S-manifold.


Real Gromov-Witten Invariants On The Moduli Space Of Genus 0 Stable Maps To A Smooth Rational Projective Space, Seongchun Kwon Jan 2008

Real Gromov-Witten Invariants On The Moduli Space Of Genus 0 Stable Maps To A Smooth Rational Projective Space, Seongchun Kwon

Turkish Journal of Mathematics

We characterize transversality, non-transversality properties on the moduli space of genus 0 stable maps to a rational projective surface. If a target space is equipped with a real structure, i.e, anti-holomorphic involution, then the results have real enumerative applications. Firstly, we can define a real version of Gromov-Witten invariants. Secondly, we can prove the invariance of Welschinger's invariant in algebraic geometric category.


Proximinality In L^1(I,X), Sharifa Al-Sharif, R. Khalil Jan 2008

Proximinality In L^1(I,X), Sharifa Al-Sharif, R. Khalil

Turkish Journal of Mathematics

Let X be a Banach space and let (I,\Omega ,\mu) be a measure space. For 1 \leq p < \infty, let L^p(I,X) denote the space of Bochner p-integrable functions defined on I with values in X. The object of this paper is to give sufficient conditions for the proximinality of L^1(I,H)+L^1(I,G) in L^1(I,X), where H and G are two proximinal subspaces of X which include as a special case the proximality of L^1(I) \stackrel{\wedge}{\otimes} G + H \stackrel{\wedge}{\otimes} L^1(I) in L^1(I \times I).