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Full-Text Articles in Physical Sciences and Mathematics

Weak-Projective Dimensions, Mohammad Javad Nikmehr, Zahra Poormahmood, Reza Nikandish Jan 2011

Weak-Projective Dimensions, Mohammad Javad Nikmehr, Zahra Poormahmood, Reza Nikandish

Turkish Journal of Mathematics

In this paper, the notions of weak-projective modules and weak-projective dimension over commutative domain R are given. It is shown that over semisimple rings with weak global dimension 1, these modules are equivalent to weak-injective modules. The weak-projective dimension measures how far away a domain is from being a Prüfer domain. Several properties of these modules are also presented.


Conjugate Convolution And Characterizations Of Inner Amenable Locally Compact Groups, Bahram Mohammadzadeh Jan 2011

Conjugate Convolution And Characterizations Of Inner Amenable Locally Compact Groups, Bahram Mohammadzadeh

Turkish Journal of Mathematics

For locally compact group G, we give some characterizations of inner amenability of G by conjugate convolution operations. Moreover, we study multiples of positive elements in group algebra L^1(G), whenever G is inner amenable.


A Class Of Generalized Shannon-Mcmillan Theorems For Arbitrary Discrete Information Source, Kangkang Wang Jan 2011

A Class Of Generalized Shannon-Mcmillan Theorems For Arbitrary Discrete Information Source, Kangkang Wang

Turkish Journal of Mathematics

In this study, a class of strong limit theorems for the relative entropy densities of random sum of arbitrary information source are discussed by constructing the joint distribution and nonnegative super martingales. As corollaries, some Shannon-McMillan theorems for arbitrary information source, mth-order Markov information source and non-memory information source are obtained and some results for the discrete information source which have been obtained by authors are extended.


On Generalized (\Alpha,\Beta)-Derivations Of Semiprime Rings, Faisal Ali, Muhammad Anwar Chaudhry Jan 2011

On Generalized (\Alpha,\Beta)-Derivations Of Semiprime Rings, Faisal Ali, Muhammad Anwar Chaudhry

Turkish Journal of Mathematics

We investigate some properties of generalized (\alpha,\beta)-derivations on semiprime rings. Among some other results, we show that if g is a generalized (\alpha,\beta)-derivation, with associated (\alpha,\beta)-derivation \delta, on a semiprime ring R such that [g(x),\alpha(x)]=0 for all x\in R, then \delta(x)[y,z]=0 for all x,y,z\in R and \delta is central. We also show that if \alpha,\nu,\tau are endomorphisms and \beta,\mu are automorphisms of a semiprime ring R and if R has a generalized (\alpha,\beta)-derivation g, with associated (\alpha,\beta)-derivation \delta, such that g([\mu(x),w(y)])=[\nu(x),w(y)]_{\alpha,\tau}, where w:R\rightarrow R is commutativity preserving, then [y,z]\delta(w(p))=0 for all y,z,p\in R.


Existence Of Mild Solutions For Abstract Mixed Type Semilinear Evolution Equations, Hong-Bo Shi, Wan-Tong Li, Hong-Rui Sun Jan 2011

Existence Of Mild Solutions For Abstract Mixed Type Semilinear Evolution Equations, Hong-Bo Shi, Wan-Tong Li, Hong-Rui Sun

Turkish Journal of Mathematics

This paper is concerned with the existence of global mild solutions and positive mild solutions to initial value problem for a class of mixed type semilinear evolution equations with noncompact semigroup in Banach spaces. The main method is based on a new fixed point theorem with respect to convex-power condensing operator.


Weingarten Quadric Surfaces In A Euclidean 3-Space, Min Hee Kim, Dae Won Yoon Jan 2011

Weingarten Quadric Surfaces In A Euclidean 3-Space, Min Hee Kim, Dae Won Yoon

Turkish Journal of Mathematics

In this paper, we study quadric surfaces in a Euclidean 3-space. Furthermore, we classify quadric surfaces in a Euclidean 3-space in terms of the Gaussian curvature and the mean curvature.


A Fredholm Alternative-Like Result On Power Bounded Operators, Ali̇ Ülger, Onur Yavuz Jan 2011

A Fredholm Alternative-Like Result On Power Bounded Operators, Ali̇ Ülger, Onur Yavuz

Turkish Journal of Mathematics

Let X be a complex Banach space and T:X\rightarrow X be a power bounded operator, i.e., \sup_{n \geq 0}\ T^n\


Rotational Embeddings In E^4 With Pointwise 1-Type Gauss Map, Kadri̇ Arslan, Bengü Kiliç Bayram, Betül Bulca, Young Ho Ki̇m, Cengi̇zhan Murathan, Günay Öztürk Jan 2011

Rotational Embeddings In E^4 With Pointwise 1-Type Gauss Map, Kadri̇ Arslan, Bengü Kiliç Bayram, Betül Bulca, Young Ho Ki̇m, Cengi̇zhan Murathan, Günay Öztürk

Turkish Journal of Mathematics

In the present article we study the rotational embedded surfaces in E^4. The rotational embedded surface was first studied by G. Ganchev and V. Milousheva as a surface in E^4. The Otsuki (non-round) sphere in E^4 is one of the special examples of this surface. Finally, we give necessary and sufficient conditions for the flat Ganchev-Milousheva rotational surface to have pointwise 1-type Gauss map.


A Note On Weighted A_P(G)-Modules, Serap Öztop Jan 2011

A Note On Weighted A_P(G)-Modules, Serap Öztop

Turkish Journal of Mathematics

Let G be a locally compact abelian group and w be a weight function on G. In this paper, we show that the space A_{p,w}(G) is a Banach module over the Figà-Talamanca Herz algebra A_p(G) and study the multiplier space from A_p(G) to A_{p,w}(G).


Hypersurfaces With Constant Mean Curvature In A Real Space Form, Shichang Shu, Sanyang Liu Jan 2011

Hypersurfaces With Constant Mean Curvature In A Real Space Form, Shichang Shu, Sanyang Liu

Turkish Journal of Mathematics

Let M^n be an n\(n \geq 3)-dimensional complete connected and oriented hypersurface in M^{n+1}(c)(c \geq 0) with constant mean curvature H and with two distinct principal curvatures, one of which is simple. We show that (1) if c=1 and the squared norm of the second fundamental form of M^n satisfies a rigidity condition (1.3), then M^n is isometric to the Riemannian product S^1(\sqrt{1-a^2}) \times S^{n-1}(a); (2) if c=0, H \neq 0 and the squared norm of the second fundamental form of M^n satisfies S \geq n^2H^2/(n-1), then M^n is isometric to the Riemannian product S^{n-1}(a)\times R or S^1(a) \times R^{n-1}


On Graded Prime And Primary Submodules, Kürşat Hakan Oral, Ünsal Teki̇r, Ahmet Göksel Ağargün Jan 2011

On Graded Prime And Primary Submodules, Kürşat Hakan Oral, Ünsal Teki̇r, Ahmet Göksel Ağargün

Turkish Journal of Mathematics

Let G be a multiplicative group. Let R be a G-graded commutative ring and M a G-graded R-module. Various properties of graded prime submodules and graded primary submodules of M are discussed. We have also discussed the graded radical of graded submodules of multiplication graded R-modules.


Coverings Of Lie Groupoids, İlhan İçen, M. Habi̇l Gürsoy, A. Fati̇h Özcan Jan 2011

Coverings Of Lie Groupoids, İlhan İçen, M. Habi̇l Gürsoy, A. Fati̇h Özcan

Turkish Journal of Mathematics

In this work we constitute the category of coverings of the Lie fundamental groupoid associated with a connected smooth manifold. We show that this category is equivalent to the category of universal coverings of a connected smooth manifold. In addition, we prove the equivalence of the category of coverings of a Lie groupoid and the category of actions of this Lie groupoid on a connected smooth manifold. Also we present two side results related to actions of Lie groupoids on the manifolds and coverings of Lie groupoids.


Krull Dimension Of Types In A Class Of First-Order Theories, Domenico Zambella Jan 2011

Krull Dimension Of Types In A Class Of First-Order Theories, Domenico Zambella

Turkish Journal of Mathematics

We study a class of first-order theories whose complete quantifier-free types with one free variable either have a trivial positive part or are isolated by a positive quantifier-free formula---plus a few other technical requirements. The theory of vector spaces and the theory fields are examples. We prove the amalgamation property and the existence of a model-companion. We show that the model-companion is strongly minimal. We also prove that the length of any increasing sequence of prime types is bounded, so every formula has finite Krull dimension.


Approximation By Complex Potentials Generated By The Gamma Function, Sorin G. Gal Jan 2011

Approximation By Complex Potentials Generated By The Gamma Function, Sorin G. Gal

Turkish Journal of Mathematics

In this paper we find the exact orders of approximation of analytic functions by the complex versions of several potentials (including the Flett potential) generated by the Gamma function and by some singular integrals.


A Beurling-Type Theorem In Bergman Spaces, Ali Abkar Jan 2011

A Beurling-Type Theorem In Bergman Spaces, Ali Abkar

Turkish Journal of Mathematics

It is known that Beurling's theorem concerning invariant subspaces is not true in the Bergman space (in contrast to the Hardy space case). However, Aleman, Richter, and Sundberg proved that every cyclic invariant subspace in the Bergman space \lpad, 0


Geometrical Objects Associated To A Substructure, Fatma Özdemi̇r, Mircea Craşmareanu Jan 2011

Geometrical Objects Associated To A Substructure, Fatma Özdemi̇r, Mircea Craşmareanu

Turkish Journal of Mathematics

Several geometric objects, namely global tensor fields of (1,1)-type, linear connections and Riemannian metrics, associated to a given substructure on a splitting of tangent bundle, are studied. From the point of view of lifting to entire manifold, two types of polynomial substructures are distinguished according to the vanishing of not of the sum of the coefficients. Conditions of parallelism for the extended structure with respect to some remarkable linear connections are given in two forms, firstly in a global description and secondly using the decomposition in distributions. A generalization of both Hermitian and anti-Hermitian geometry is proposed.


On The Uniqueness Of Strongly Flat Covers Of Cyclic Acts, Majid Ershad, Roghaieh Khosravi Jan 2011

On The Uniqueness Of Strongly Flat Covers Of Cyclic Acts, Majid Ershad, Roghaieh Khosravi

Turkish Journal of Mathematics

In [1], strongly flat covers of cyclic acts are discussed and it is asked if strongly flat covers are unique. From this point of view, in this paper we give numerous classes of monoids over which strongly flat covers of cyclic acts are unique.


On Almost Complex Structures In The Cotangent Bundle, Ari̇f Sali̇mov, Aydin Gezer, Seher Aslanci Jan 2011

On Almost Complex Structures In The Cotangent Bundle, Ari̇f Sali̇mov, Aydin Gezer, Seher Aslanci

Turkish Journal of Mathematics

E. M. Patterson and K. Yano studied vertical and complete lifts of tensor fields and connections from a manifold M_n to its cotangent bundle T^{\ast} (M_n). Afterwards, K. Yano studied the behavior on the cross-section of the lifts of tensor fields and connections on a manifold M_n to T^{\ast} (M_n) and proved that when \varphi defines an integrable almost complex structure on M_n, its complete lift ^C \varphi is a complex structure. The main result of the present paper is the following theorem: Let \varphi be an almost complex structure on a Riemannian manifold M_n. Then the complete lift ^C …


Gpq Modules And Generalized Armendariz Modules, Liang Zhao, Xiaosheng Zhu Jan 2011

Gpq Modules And Generalized Armendariz Modules, Liang Zhao, Xiaosheng Zhu

Turkish Journal of Mathematics

Let M_R be a right R-module. We introduce the concept of right generalized p.q.-Baer modules (or simply, right GPQ modules) to extend the notion of right p.q.-Baer modules. We study on the relationship between the GPQ property of a module M_R and various quasi-Armendariz properties. We prove that every right GPQ module is a quasi-Armendariz module. As a sequence, we obtain a general form of some known results considering the p.q.Baer property of a ring, some known results are extended. Moreover, we prove that for the formal triangular ring R constructed from a pair of rings S, T and a …


The Cyclicity Of The Period Annulus Of A Quadratic Reversible System With One Center Of Genus One, Linping Peng, Yannan Sun Jan 2011

The Cyclicity Of The Period Annulus Of A Quadratic Reversible System With One Center Of Genus One, Linping Peng, Yannan Sun

Turkish Journal of Mathematics

This paper is concerned with a quadratic reversible and non-Hamiltonian system with one center of genus one. By using the properties of related elliptic integrals and the geometry of some planar curves defined by them, we prove that the cyclicity of the period annulus of the considered system under small quadratic perturbations is two. This verifies Gautier's conjecture about the cyclicity of the related period annulus.


Cyclic Codes Over {Z_2+Uz_2+U^2z_2+\Ldots+U^{K-1}Z_2}, Mohammed Al Ashker, Mohammed Hamoudeh Jan 2011

Cyclic Codes Over {Z_2+Uz_2+U^2z_2+\Ldots+U^{K-1}Z_2}, Mohammed Al Ashker, Mohammed Hamoudeh

Turkish Journal of Mathematics

In this paper, we study the structure of cyclic codes of an arbitrary length n over the ring Z_2+uZ_2+u^2Z_2+\ldots+u^{k-1}Z_2, where u^k=0. Also we study the rank for these codes, and we find their minimal spanning sets. This study is a generalization and extension of the work in reference [1].


Some Products Involving The Fourth Greek Letter Family Element \Tilde{\Delta}_S In The Adams Spectral Sequence, Xiu-Gui Liu, He Wang Jan 2011

Some Products Involving The Fourth Greek Letter Family Element \Tilde{\Delta}_S In The Adams Spectral Sequence, Xiu-Gui Liu, He Wang

Turkish Journal of Mathematics

Let p be an odd prime and A be the mod p Steenrod algebra. For computing the stable homotopy groups of spheres with the classical Adams spectral sequence, we must compute the E_2-term of the Adams spectral sequence, Ext_A^{\ast,\ast} (Z_p,Z_p). In this paper we prove that in the cohomology of A, the product k_0 h_n \tilde \delta _{s + 4} \in Ext_A^{s + 7, t(s,n) + s} (Z_p, Z_p), is nontrivial for n \geq 5, and trivial for n=3, 4, where \tilde\delta_{s + 4} is actually \tilde\alpha_{s + 4}^{(4)} described by Wang and Zheng, p \geq 11, 0 \leq s < p - 4 and t(s,n)=2(p-1)[(s + 2) + (s + 4)p + (s + 3)p^2 + (s + 4)p^3 + p^n].


Existence Theory For Positive Solutions Of P-Laplacian Multi-Point Bvps On Time Scales, You-Hui Su Jan 2011

Existence Theory For Positive Solutions Of P-Laplacian Multi-Point Bvps On Time Scales, You-Hui Su

Turkish Journal of Mathematics

This paper is concerned with the one-dimensional p-Laplacian multi-point boundary value problem on time scales T: (\varphi_p(u^{\Delta}))^{\nabla} + h(t)f(u) = 0, t \in [0,T]_T, subject to multi-point boundary conditions u(0) - B_0(\sum_{i=1}^{m-2}a_i u^{\Delta}(\xi_i)) = 0, u^{\Delta}(T) = 0, or u^{\Delta}(0) = 0, u(T) + B_1(\sum_{i=1}^{m-2}b_iu^{\Delta}(\xi'_i)) = 0, where \varphi_p(u) is p-Laplacian operator, i.e., \varphi_p(u = u ^{p-2}u, p>1, \xi_i,\xi'_i\in [0,T]_T, m \geq 3 and satisfy 0 \leq \xi_1 < \xi_2 < ... < \xi_{m-2} < \rho(T), \sigma(0) < \xi'_1 < \xi'_2 < ... < \xi'_{m-2} \leq T, a_i, b_i\in [0,\infty) (i=1,2,..., m-2). Some new sufficient conditions are obtained for the existence of at least one positive solution by using Krasnosel'skii's fixed-point theorem and new sufficient conditions are obtained for the existence of twin, triple or arbitrary odd positive solutions by using generalized Avery and Henderson fixed-point theorem and Avery-Peterson fixed-point theorem. Our results include and extend some known results. As applications, two examples are given to illustrate the main results and their differences. These results are new even for the special cases of continuous and discrete equations, as well as in the general time scale setting.


Universal Inequalities And Bounds For Weighted Eigenvalues Of The Schrödinger Operator On The Heisenberg Group, Hejun Sun Jan 2011

Universal Inequalities And Bounds For Weighted Eigenvalues Of The Schrödinger Operator On The Heisenberg Group, Hejun Sun

Turkish Journal of Mathematics

For a bounded domain \Omega in the Heisenberg group H^n, we investigate the Dirichlet weighted eigenvalue problem of the Schrödinger operator - \Delta_{H^n} +V, where \Delta_{H^n} is the Kohn Laplacian and V is a nonnegative potential. We establish a Yang-type inequality for eigenvalues of this problem. It contains the sharpest result for \Delta_{H^n} in [17] of Soufi, Harrel II and Ilias. Some estimates for upper bounds of higher order eigenvalues and the gaps of any two consecutive eigenvalues are also derived. Our results are related to some previous results for the Laplacian \Delta and the Schrödinger operator -\Delta+V on a …


Some Properties Of Associate And Presimplifiable Rings, Manal Ghanem Jan 2011

Some Properties Of Associate And Presimplifiable Rings, Manal Ghanem

Turkish Journal of Mathematics

In this paper we study some properties of associate and presimplifiable rings. We give a characterization of the associate (resp., domainlike) pullback P of R_1 \rightarrow{R_3} \leftarrow{R_2}, where R_1 and R_2 are two presimplifiable (resp., domainlike) rings. We prove that R is presimplifiable ring if and only if the factor ring R/{nil(R)} is presimplifiable and the ideal nil(R) is presimplifiable. Then we investigate the associate and presimplifiable property of the dual rings {R[x]/\langle{x^2}\rangle} and its modules through the base ring R and its modules.


Probabilities For Absolute Irreducibility Of Multivariate Polynomials By The Polytope Method, Fati̇h Koyuncu, Ferruh Özbudak Jan 2011

Probabilities For Absolute Irreducibility Of Multivariate Polynomials By The Polytope Method, Fati̇h Koyuncu, Ferruh Özbudak

Turkish Journal of Mathematics

Motivated by the Dubickas's result in [1], which computes the probability of the irreducible polynomials by Eisenstein's criterion for some families of polynomials in Z[x], we calculate the probabilities which represent the ratio of absolutely irreducible multivariate polynomials by the polytope method in some families of polynomials over arbitrary fields.


Module Classes And The Lifting Property, Muhammet Tamer Koşan Jan 2011

Module Classes And The Lifting Property, Muhammet Tamer Koşan

Turkish Journal of Mathematics

Let R be a ring. A collection of R-modules containing the zero module and closed under isomorphisms will be denoted by X. An R-module M is said to be X-lifting if for every X-submodule N of M there exists A \leq N such that M=A \oplus B and N \cap B is small in B [11]. In the present paper, we consider the question: Can we characterize X-lifting modules via objects of the class X?


Top Generalized Local Cohomology Modules, Amir Mafi Jan 2011

Top Generalized Local Cohomology Modules, Amir Mafi

Turkish Journal of Mathematics

Let (R,m) be a commutative Noetherian local ring and M, N two non-zero finitely generated R-modules with d(M)=n


Some Results On G-Frames In Hilbert Spaces, Abdolaziz Abdollahi, Elham Rahimi Jan 2011

Some Results On G-Frames In Hilbert Spaces, Abdolaziz Abdollahi, Elham Rahimi

Turkish Journal of Mathematics

In this paper we show that every g-frame for a Hilbert space H can be represented as a linear combination of two g-orthonormal bases if and only if it is a g-Riesz basis. We also show that every g-frame can be written as a sum of two tight g-frames with g-frame bounds one or a sum of a g-orthonormal basis and a g-Riesz basis for H. We further give necessary and sufficient conditions on g-Bessel sequences {\Lambda_i \in L (H,H_i) : i \in J} and {\Gamma_i \in L(H,H_i): i \in J} and operators L_1, L_2 on H so that {\Lambda_iL_1+\Gamma_iL_2: …


Properties Of Rd-Projective And Rd-Injective Modules, Lixin Mao Jan 2011

Properties Of Rd-Projective And Rd-Injective Modules, Lixin Mao

Turkish Journal of Mathematics

In this paper, we first study RD-projective and RD-injective modules using, among other things, covers and envelopes. Some new characterizations for them are obtained. Then we introduce the RD-projective and RD-injective dimensions for modules and rings. The relations between the RD-homological dimensions and other homological dimensions are also investigated.