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Full-Text Articles in Mathematics

An Exhaustive Computer Search For Finding New Curves With Many Points Among Fibre Products Of Two Kummer Covers Over F_5 And F_7, Ferruh Özbudak, Burcu Gülmez Temür, Oğuz Yayla Jan 2013

An Exhaustive Computer Search For Finding New Curves With Many Points Among Fibre Products Of Two Kummer Covers Over F_5 And F_7, Ferruh Özbudak, Burcu Gülmez Temür, Oğuz Yayla

Turkish Journal of Mathematics

In this paper we make an exhaustive computer search for finding new curves with many points among fibre products of 2 Kummer covers of the projective line over F_5 and F_7. At the end of the search, we have 12 records and 6 new entries for the current Table of Curves with Many Points. In particular, we observe that the fibre product y_1^3 = \frac{5(x + 2)(x + 5)}{x}, y_2^3 = \frac{3x^2(x + 5)}{x + 3} over F_7 has genus 7 with 36 rational points. As this coincides with the Ihara bound, we conclude that the maximum number N_7(7) of …


On The Existence Of Nonzero Injective Covers And Projective Envelopes Of Modules, Xiaoxiang Zhang, Xianmei Song Jan 2013

On The Existence Of Nonzero Injective Covers And Projective Envelopes Of Modules, Xiaoxiang Zhang, Xianmei Song

Turkish Journal of Mathematics

In general, the injective cover (projective envelope) of a simple module can be zero. A ring R is called a weakly left V-ring (strongly left Kasch ring) if every simple left R-module has a nonzero injective cover (projective envelope). It is proven that every nonzero left R-module has a nonzero injective cover if and only if R is a left Artinian weakly left V-ring. Dually, every nonzero left R-module has a nonzero projective envelope if and only if R is a left perfect right coherent strongly left Kasch ring. Some related rings and examples are considered.


On The Krull Dimension Of Endo-Bounded Modules, Ahmad Haghany, Majid Mazrooei, Mohamad Reza Vedadi Jan 2013

On The Krull Dimension Of Endo-Bounded Modules, Ahmad Haghany, Majid Mazrooei, Mohamad Reza Vedadi

Turkish Journal of Mathematics

Modules in which every essential submodule contains an essential fully invariant submodule are called endo-bounded. Let M be a nonzero module over an arbitrary ring R and X = Spec_2(M_R), the set of all fully invariant L_2-prime submodules of M_R. If M_R is a quasi-projective L_2-Noetherian such that (M/P)_R is endo-bounded for any P \in X, then it is shown that the Krull dimension of M_R is at most the classical Krull dimension of the poset X. The equality of these dimensions and some applications are obtained for certain modules. This gives a generalization of a well-known result on right …


On The Pollard Decomposition Method Applied To Some Jacobi--Sobolev Expansions, Francisco Marcellán, Yamilet Quintana, Alejandro Urieles Jan 2013

On The Pollard Decomposition Method Applied To Some Jacobi--Sobolev Expansions, Francisco Marcellán, Yamilet Quintana, Alejandro Urieles

Turkish Journal of Mathematics

Let {q_n^{(\alpha,\beta)}}_{n \geq 0} be the sequence of polynomials orthonormal with respect to the Sobolev inner product \langle f,g\rangle_S:=\int_{-1}^1f(x)g(x)w^{(\alpha,\beta)}(x)dx+\int_{-1}^1f'(x)g'(x)w^{(\alpha+1,\beta+1)}(x)dx, where w^{(\alpha,\beta)}(x)=(1-x)^{\alpha}(1+x)^{\beta}, x\in [-1,1] and \alpha,\beta>-1. This paper explores the convergence in the W^{1,p}\left((-1,1), (w^{(\alpha,\beta)},w^{(\alpha+1,\beta+1)})\right) norm of the Fourier expansion in terms of {q_n^{(\alpha,\beta)}}_{n\geq 0} with 1< p


Complemented Invariant Subspaces Of Structural Matrix Algebras, Mustafa Akkurt, Emi̇ra Akkurt, George Phillip Barker Jan 2013

Complemented Invariant Subspaces Of Structural Matrix Algebras, Mustafa Akkurt, Emi̇ra Akkurt, George Phillip Barker

Turkish Journal of Mathematics

In this paper, we explore when the lattice of invariant subspaces of a structural matrix algebra can be complemented. We give several equivalent conditions for this lattice to be a Boolean algebra.


Magnetic Field-Induced Stability Of A Specific Configuration And The Asymptotic Behavior Of Minimizers In Nematic Liquid Crystals, Junichi Aramaki Jan 2013

Magnetic Field-Induced Stability Of A Specific Configuration And The Asymptotic Behavior Of Minimizers In Nematic Liquid Crystals, Junichi Aramaki

Turkish Journal of Mathematics

We consider the stability of a specific nematic liquid crystal configuration under an applied magnetic field. We impose the strong anchoring condition, and we allow the boundary data to be nonconstant and also the applied field to be nonconstant. Thus, we shall extend the results of Lin and Pan in 2007. We show that for some specific configuration there exist 2 critical values H_n and H_{sh} of applied magnetic field. When the intensity of the magnetic field is smaller than H_n, the configuration of the energy is only a global minimizer, when the intensity is between H_n and H_{sh}, the …


Semi-Slant And Bi-Slant Submanifolds Of Almost Contact Metric 3-Structure Manifolds, Fereshteh Malek, Mohammad Bagher Kazemi Balgeshir Jan 2013

Semi-Slant And Bi-Slant Submanifolds Of Almost Contact Metric 3-Structure Manifolds, Fereshteh Malek, Mohammad Bagher Kazemi Balgeshir

Turkish Journal of Mathematics

In this paper we introduce the notions of semi-slant and bi-slant submanifolds of an almost contact 3-structure manifold. We give some examples and characterization theorems about these submanifolds. Moreover, the distributions of semi-slant submanifolds of 3-cosymplectic and 3-Sasakian manifolds are studied.


Colombeau Solutions Of A Nonlinear Stochastic Predator--Prey Equation, Uluğ Çapar Jan 2013

Colombeau Solutions Of A Nonlinear Stochastic Predator--Prey Equation, Uluğ Çapar

Turkish Journal of Mathematics

The solution of a random semilinear hyperbolic system with singular initial data is sought as a random Colombeau distribution. The product of 2 additive white noises is well tackled within the theory of random Colombeau distributions. In the special case of a random predator--prey system, the exact Colombeau solution is obtained under some assumptions when the process is driven by doubly reflected Brownian motions.


Some Results On Cyclic Codes Over The Ring R_{2,M}, Reza Sobhani, Maryam Molakarimi Jan 2013

Some Results On Cyclic Codes Over The Ring R_{2,M}, Reza Sobhani, Maryam Molakarimi

Turkish Journal of Mathematics

Let R_{k,m} be the ring F_{2^m}[u_1,u_2,...,u_k]/\gen u_i^2, u_iu_j-u_ju_i. In this paper, cyclic codes of arbitrary length n over the ring R_{2,m} are completely characterized in terms of unique generators and a way for determination of these generators is investigated. A F_{2^m}-basis for these codes is also derived from this representation. Moreover, it is proven that there exists a one-to-one correspondence between cyclic codes of length 2n, n odd, over the ring R_{k-1,m} and cyclic codes of length n over the ring R_{k,m}. By determining the complete structure of cyclic codes of length 2 over R_{2,m}, a mass formula for the …


Strong Solution For A High Order Boundary Value Problem With Integral Condition, Ahcene Merad, Ahmed Lakhdar Marhoune Jan 2013

Strong Solution For A High Order Boundary Value Problem With Integral Condition, Ahcene Merad, Ahmed Lakhdar Marhoune

Turkish Journal of Mathematics

The present paper is devoted to a proof of the existence and uniqueness of strong solution for a high order boundary value problem with integral condition. The proof is based by a priori estimate and on the density of the range of the operator generated by the studied problem.


On Integrability Of Golden Riemannian Structures, Aydin Gezer, Nejmi̇ Cengi̇z, Arif Salimov Jan 2013

On Integrability Of Golden Riemannian Structures, Aydin Gezer, Nejmi̇ Cengi̇z, Arif Salimov

Turkish Journal of Mathematics

The main purpose of the present paper is to study the geometry of Riemannian manifolds endowed with Golden structures. We discuss the problem of integrability for Golden Riemannian structures by using a \phi-operator which is applied to pure tensor fields. Also, the curvature properties for Golden Riemannian metrics and some properties of twin Golden Riemannian metrics are investigated. Finally, some examples are presented.


(P,\\Lambda)-Koszul Algebras And Modules, Ii, Jiafeng Lu Jan 2013

(P,\\Lambda)-Koszul Algebras And Modules, Ii, Jiafeng Lu

Turkish Journal of Mathematics

This paper is a continuous work of [14], where the notions of (p,\lambda)-Koszul algebra and (p,\lambda)-Koszul module were first introduced. More precisely, some new criteria for a positively graded algebra to be (p,\lambda)-Koszul are provided. We also generalize (p,\lambda)-Koszul objects to the nongraded case and define the so-called quasi-(p,\lambda)-Koszul objects. Further, the relationships between (quasi-) (p,\lambda)-Koszul modules and minimal Horseshoe Lemma are established.


On Some Results On Ip-Graphs, Roghayeh Hafezieh, Moohammadali Iranmanesh Jan 2013

On Some Results On Ip-Graphs, Roghayeh Hafezieh, Moohammadali Iranmanesh

Turkish Journal of Mathematics

The IP-graph of a naturally valenced association scheme and some of its properties have been studied recently. In this paper we introduce the bipartite version of this graph for a naturally valenced association scheme (X,S), denoted by BIP(S). We also investigate some of its properties.


On The Centroid Of Prime Semirings, Hasret Yazarli, Mehmet Ali̇ Öztürk Jan 2013

On The Centroid Of Prime Semirings, Hasret Yazarli, Mehmet Ali̇ Öztürk

Turkish Journal of Mathematics

We define and study the extended centroid of a prime semiring. We show that the extended centroid is a semifield and give some properties of the centroid of a right multiplicatively cancellable prime semiring.


Second Order Approximations In Sequential Point Estimation Of The Probability Of Zero In Poisson Distribution, Eisa Mahmoudi, Mohammad Hatami Kamin Jan 2013

Second Order Approximations In Sequential Point Estimation Of The Probability Of Zero In Poisson Distribution, Eisa Mahmoudi, Mohammad Hatami Kamin

Turkish Journal of Mathematics

In the analysis of the count data, the Poisson model becomes overtly restrictive in the case of over-dispersed or under-dispersed data. When count data are under-dispersed, specific models such as generalized linear models (GLM) are proposed. Other examples are the zero-inflated Poisson model (ZIP) and zero-truncated Poisson model (ZTP), which have been used in literature to deal with an excess or absence of zeros in count data. Thus having a knowledge of the probability of zeros and its estimation in Poisson distribution can be significant and useful. Some estimation problems with unknown parameter cannot attain minimum risk where the sample …


Generalized Derivations Of Prime Rings On Multilinear Polynomials With Annihilator Conditions, Nurcan Argaç, Çağri Demi̇r Jan 2013

Generalized Derivations Of Prime Rings On Multilinear Polynomials With Annihilator Conditions, Nurcan Argaç, Çağri Demi̇r

Turkish Journal of Mathematics

Let K be a commutative ring with unity, R be a prime K-algebra with characteristic not 2, U be the right Utumi quotient ring of R, C the extended centroid of R, I a nonzero right ideal of R and a a fixed element of R. Let g be a generalized derivation of R and f(X_1,..., X_n) a multilinear polynomial over K. If ag(f(x_1,...,x_n))f(x_1,...,x_n)=0 for all x_1,...,x_n \in I, then one of the following holds: (1) aI=ag(I)=0; (2) g(x)=bx+[c,x] for all x\in R, where b,c\in U. In this case either [c,I]I=0=abI or aI=0=a(b+c)I; (3) [f(X_1,...,X_n),X_{n+1}]X_{n+2} is an identity for I.


On The Nilpotent Graph Of A Ring, Mohammad Javad Nikmehr, Soheila Khojasteh Jan 2013

On The Nilpotent Graph Of A Ring, Mohammad Javad Nikmehr, Soheila Khojasteh

Turkish Journal of Mathematics

Let R be a ring with unity. The nilpotent graph of R, denoted by \Gamma_N(R), is a graph with vertex set Z_N(R)^* = {0 \neq x \in R \mid xy \in N(R) for some 0 \neq y \in R}; and two distinct vertices x and y are adjacent if and only if xy \in N(R), where N(R) is the set of all nilpotent elements of R. Recently, it has been proved that if R is a left Artinian ring, then diam(\Gamma_N(R)) \leq 3. In this paper, we present a new proof for the above result, where R is a finite …


Complex Symplectic Geometry With Applications To Vector Differential Operators, Chuan Fu Yang Jan 2013

Complex Symplectic Geometry With Applications To Vector Differential Operators, Chuan Fu Yang

Turkish Journal of Mathematics

Let l(y) be a formally self-adjoint vector-valued differential expression of order n on an interval (a, \infty)(-\infty \leq a < \infty) with complex matrix-valued function coefficients and finite equal deficiency indices. In this paper, applying complex symplectic algebra, we give a reformulation for self-adjoint domains of the minimal operator associated with l(y) and classify them.


Global Existence, Decay And Blow Up Solutions For Coupled Nonlinear Wave Equations With Damping And Source Terms, Erhan Pi̇şki̇n, Necat Polat Jan 2013

Global Existence, Decay And Blow Up Solutions For Coupled Nonlinear Wave Equations With Damping And Source Terms, Erhan Pi̇şki̇n, Necat Polat

Turkish Journal of Mathematics

We study the initial-boundary value problem for a system of nonlinear wave equations with nonlinear damping and source terms, in a bounded domain. The decay estimates of the energy function are established by using Nakao's inequality. The nonexistence of global solutions is discussed under some conditions on the given parameters.


L^P Solutions Of Infinite Time Interval Bsdes And The Corresponding G-Expectations And G-Martingales, Zhaojun Zong Jan 2013

L^P Solutions Of Infinite Time Interval Bsdes And The Corresponding G-Expectations And G-Martingales, Zhaojun Zong

Turkish Journal of Mathematics

In this paper we study the existence and uniqueness theorem for L^p (1


On Quasiconformal Harmonic Mappings Lifting To Minimal Surfaces, Hakan Mete Taştan, Yaşar Polatoğlu Jan 2013

On Quasiconformal Harmonic Mappings Lifting To Minimal Surfaces, Hakan Mete Taştan, Yaşar Polatoğlu

Turkish Journal of Mathematics

We prove a growth theorem for a function to belong to the class \sum(\mu;a) and generalize a Weierstrass-Enneper representation type theorem for the minimal surfaces given in [5] to spacelike minimal surfaces which lie in 3-dimensional Lorentz-Minkowski space L^3. We also obtain some estimates of the Gaussian curvature of the minimal surfaces in 3-dimensional Euclidean space R^3 and of the spacelike minimal surfaces in L^3.


A Note On Unmixed Ideals Of Veronese Bi-Type, Monica La Barbiera Jan 2013

A Note On Unmixed Ideals Of Veronese Bi-Type, Monica La Barbiera

Turkish Journal of Mathematics

We classify the unmixed ideals of Veronese bi-type and in some cases we give a description of their associated prime ideals.


G-Frames As Special Frames, Abas Askarizadeh, Mohammad Ali Dehghan Jan 2013

G-Frames As Special Frames, Abas Askarizadeh, Mohammad Ali Dehghan

Turkish Journal of Mathematics

G-frames are generalizations of ordinary frames for Hilbert spaces. In the present paper we study frames, and operators on a special separable Hilbert C^*-module, B(H,K), where H and K are Hilbert spaces, and we prove that every g-frame for H is a frame for B(H,K) and vice versa. Also, we derive some relationships between g-Riesz bases for H and Riesz bases in B(H,K). Similar results for orthogonal bases will be discussed.


On Pseudo Semi-Projective Modules, Truong Cong Quynh Jan 2013

On Pseudo Semi-Projective Modules, Truong Cong Quynh

Turkish Journal of Mathematics

A right R-module M is called semi-projective if, for any submodule N of M, every epimorphism \pi: M \rightarrow N and every homomorphism \alpha: M \rightarrow N, there exists a homomorphism \beta: M \rightarrow M such that \pi \beta = \alpha (see [11]). In this paper, we consider some generalizations of semi-projective module, that is quasi pseudo principally projective module. Some properties of this class of module are studied.


Generating Systems Of Differential Invariants And The Theorem On Existence For Curves In The Pseudo-Euclidean Geometry}, Djavvat Khadjiev, İdri̇s Ören, Ömer Pekşen Jan 2013

Generating Systems Of Differential Invariants And The Theorem On Existence For Curves In The Pseudo-Euclidean Geometry}, Djavvat Khadjiev, İdri̇s Ören, Ömer Pekşen

Turkish Journal of Mathematics

Let M(n, p) be the group of all motions of an n-dimensional pseudo-Euclidean space of index p. It is proved that the complete system of M(n,p)-invariant differential rational functions of a path (curve) is a generating system of the differential field of all M(n,p)-invariant differential rational functions of a path (curve), respectively. A fundamental system of relations between elements of the complete system of M(n,p)-invariant differential rational functions of a path (curve) is described.


Rings Over Which Every Module Has A Flat \\Delta-Cover, Pinar Aydoğdu Jan 2013

Rings Over Which Every Module Has A Flat \\Delta-Cover, Pinar Aydoğdu

Turkish Journal of Mathematics

Let M be a module. A \delta-cover of M is an epimorphism from a module F onto M with a \delta-small kernel. A \delta-cover is said to be a flat \delta-cover in case F is a flat module. In the present paper, we investigate some properties of (flat) \delta-covers and flat modules having a projective \delta-cover. Moreover, we study rings over which every module has a flat \delta-cover and call them right generalized \delta-perfect rings. We also give some characterizations of \delta-semiperfect and \delta-perfect rings in terms of locally (finitely, quasi-, direct-) projective \delta-covers and flat \delta-covers.


Formulas For The Fourier Coefficients Of Cusp Form For Some Quadratic Forms (Correction To A Paper By Ahmet Tekcan With The Same Title), Bariş Kendi̇rli̇ Jan 2013

Formulas For The Fourier Coefficients Of Cusp Form For Some Quadratic Forms (Correction To A Paper By Ahmet Tekcan With The Same Title), Bariş Kendi̇rli̇

Turkish Journal of Mathematics

In this study M_1(\Gamma _0(3) ,\chi _{-3}) , M_2(\Gamma_0(5), \chi _5) and M_3(\Gamma _0(7),\chi _{-7}) have been examined and the formulas for the Fourier Coefficients of theta series and the representation number of positive integers by some quadratic forms 3x_1^2+3x_1x_2+x_2^2, 5(x_1^2+x_1x_2+x_1x_3+x_1x_4+x_2^2+x_2x_3+ x_2x_4+x_3^2+x_3x_4)+2x_4^2, and 7(x_1^2+x_1x_2+x_1x_3+x_1x_4+x_1x_5+x_2^2+x_2x_3+x_2x_4+x_2x_5+ x_3^2+x_3x_4+x_3x_5+x_4^2+x_4x_5+x_5^2+7(x_1x_6+x_2x_6+x_3x_6+ x_4x_6+x_5x_6)+3x_6^2, are determined. This work is a correction to a paper of the same title by Ahmet Tekcan [5].


On The Existence Of (400, 57, 8) Non-Abelian Difference Sets, Adegoke Solomon Osifodunrin Jan 2013

On The Existence Of (400, 57, 8) Non-Abelian Difference Sets, Adegoke Solomon Osifodunrin

Turkish Journal of Mathematics

Difference sets with parameters (\frac{q^{d + 1} - 1}{q - 1}, \frac{q^d - 1}{q - 1}, \frac{q^{d - 1} - 1}{q - 1}), where q is a prime power and d \geq 1, are known to exist in cyclic groups and are called classical Singer difference sets. We study a special case of this family with q = 7 and d = 3 in search of more difference sets. According to GAP, there are 220 groups of order 400 out of which 10 are abelian. E. Kopilovich and other authors showed that the remaining nine abelian groups of order 400 …


Gorenstein Transpose With Respect To A Semidualizing Bimodule, Zengfeng Liu, Xiaoguang Yan Jan 2013

Gorenstein Transpose With Respect To A Semidualizing Bimodule, Zengfeng Liu, Xiaoguang Yan

Turkish Journal of Mathematics

Let S and R be rings and _SC_R be a semidualizing bimodule. We first give the definitions of C-transpose and n-C-torsionfree and give a criterion for a module A to be G_C-projective by some property of the C-transpose of A. Then we introduce the notion of C-Gorenstein transpose of a module over two-sided Noetherian rings. We prove that a module M in \mod R^{op} is a C-Gorenstein transpose of a module A \in \mod S if and only if M can be embedded into a C-transpose of A with the cokernel G_C-projective. Finally we investigate some homological properties of the …


Algorithm To Solve Certain Ternary Quartic Diophantine Equations, Laszlo Szalay Jan 2013

Algorithm To Solve Certain Ternary Quartic Diophantine Equations, Laszlo Szalay

Turkish Journal of Mathematics

In this paper, we develop an algorithm to solve completely the Diophantine equation F(x,y)=z^2, where the quartic inhomogeneous polynomial F(x,y) with integer coefficients satisfies certain technical conditions. The procedure is an extension of the version of Runge's method given by Poulakis.