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Full-Text Articles in Mathematics

The Property Of Real Hypersurfaces In 2-Dimensional Complex Space Form With Ricci Operator, Dong Ho Lim, Woon Ha Sohn, Seong Soo Ahn Jan 2014

The Property Of Real Hypersurfaces In 2-Dimensional Complex Space Form With Ricci Operator, Dong Ho Lim, Woon Ha Sohn, Seong Soo Ahn

Turkish Journal of Mathematics

Let M be a real hypersurface in a complex space form M_2(c), c \neq 0. In this paper, we prove that S \phi=\phi S on M if and only if M is pseudo-Einstein.


An Alternative Approach To The Adem Relations In The Mod 2 Steenrod Algebra, Neşet Deni̇z Turgay Jan 2014

An Alternative Approach To The Adem Relations In The Mod 2 Steenrod Algebra, Neşet Deni̇z Turgay

Turkish Journal of Mathematics

The Leibniz--Hopf algebra F is the free associative algebra over Z on one generator S^n in each degree n>0, with coproduct given by \Delta(S^n) = \sum_{i+j=n} S^i \otimes S^j. We introduce a new perspective on the Adem relations in the mod 2 Steenrod algebra A_2 by studying the map \pi^\ast dual to the Hopf algebra epimorphism \pi: F \otimes Z/2 \to A_2. We also express Milnor's Hopf algebra conjugation formula in A_2^\ast in a different form and give a new approach for the conjugation invariant problem in A_2^\ast.


Population Dynamical Behaviors Of Stochastic Logistic System With Jumps, Ruihua Wu, Ke Wang Jan 2014

Population Dynamical Behaviors Of Stochastic Logistic System With Jumps, Ruihua Wu, Ke Wang

Turkish Journal of Mathematics

This paper is concerned with a stochastic logistic model driven by martingales with jumps. In the model, generalized noise and jump noise are taken into account. This model is new and more feasible. The explicit global positive solution of the system is presented, and then sufficient conditions for extinction and persistence are established. The critical value of extinction, nonpersistence in the mean, and weak persistence in the mean are obtained. The path-wise and moment properties are also investigated. Finally, some simulation figures are introduced to illustrate the main results.


On A Generalization Of Kelly's Combinatorial Lemma, Aymen Ben Amira, Jamel Dammak, Hamza Si Kaddour Jan 2014

On A Generalization Of Kelly's Combinatorial Lemma, Aymen Ben Amira, Jamel Dammak, Hamza Si Kaddour

Turkish Journal of Mathematics

Kelly's combinatorial lemma is a basic tool in the study of Ulam's reconstruction conjecture. A generalization in terms of a family of t -elements subsets of a v -element set was given by Pouzet. We consider a version of this generalization modulo a prime p. We give illustrations to graphs and tournaments.


Frobenius-Like Groups As Groups Of Automorphisms, Güli̇n Ercan, İsmai̇l Şuayi̇p Güloğlu, Evgeny Khukhro Jan 2014

Frobenius-Like Groups As Groups Of Automorphisms, Güli̇n Ercan, İsmai̇l Şuayi̇p Güloğlu, Evgeny Khukhro

Turkish Journal of Mathematics

A finite group FH is said to be Frobenius-like if it has a nontrivial nilpotent normal subgroup F with a nontrivial complement H such that FH/[F,F] is a Frobenius group with Frobenius kernel F/[F,F]. Such subgroups and sections are abundant in any nonnilpotent finite group. We discuss several recent results about the properties of a finite group G admitting a Frobenius-like group of automorphisms FH aiming at restrictions on G in terms of C_G(H) and focusing mainly on bounds for the Fitting height and related parameters. Earlier such results were obtained for Frobenius groups of automorphisms; new theorems for Frobenius-like …


Hilbert Series Of The Braid Monoid Mb_4 In Band Generators, Zaffar Iqbal, Shamaila Yousaf Jan 2014

Hilbert Series Of The Braid Monoid Mb_4 In Band Generators, Zaffar Iqbal, Shamaila Yousaf

Turkish Journal of Mathematics

L. A. Bokut gave a Gröbner--Shirshov basis of the braid group B_n in band generators. Using this presentation and solving all the ambiguities we construct a linear system for irreducible words and compute the Hilbert series of the braid monoid MB_4.


Gradient Estimates For The Porous Medium Type Equation On Smooth Metric Measure Space, Deng Yihua Jan 2014

Gradient Estimates For The Porous Medium Type Equation On Smooth Metric Measure Space, Deng Yihua

Turkish Journal of Mathematics

The porous medium equation arises in different applications to model diffusive phenomena. In this paper, we obtain several gradient estimates for some porous medium type equations on smooth metric measure space with N-Bakry-Emery Ricci tensor bounded from below. In particular, we improve and generalize some current gradient estimates for the porous medium equations.


Disjoint Supercyclic Powers Of Weighted Shifts On Weighted Sequence Spaces, Yu-Xia Liang, Ze-Hua Zhou Jan 2014

Disjoint Supercyclic Powers Of Weighted Shifts On Weighted Sequence Spaces, Yu-Xia Liang, Ze-Hua Zhou

Turkish Journal of Mathematics

We characterize the disjoint supercyclicity of finitely many different powers of weighted shifts acting on the weighted sequence spaces l^2(N,w), c_0(N,w) , and l^2(Z,w), c_0(Z,w), where w=(w_i)_i is a positive weight sequence satisfying w_i \geq 1 for every i\in N (or i\in Z).


Some New Associated Curves Of A Frenet Curve In E^3 And E^4, Nesi̇be Maci̇t, Mustafa Düldül Jan 2014

Some New Associated Curves Of A Frenet Curve In E^3 And E^4, Nesi̇be Maci̇t, Mustafa Düldül

Turkish Journal of Mathematics

In this paper, firstly, we define a W -direction curve and W -rectifying curve of a Frenet curve in 3-dimensional Euclidean space E^3 by using the unit Darboux vector field W of the Frenet curve and give some characterizations together with the relationships between the curvatures of each associated curve. We also introduce a V -direction curve, which is associated with a curve lying on an oriented surface in E^3. Later, some new associated curves of a Frenet curve are defined in E^4.


Notes On The Tangent Bundle With Deformed Complete Lift Metric, Aydin Gezer, Mustafa Özkan Jan 2014

Notes On The Tangent Bundle With Deformed Complete Lift Metric, Aydin Gezer, Mustafa Özkan

Turkish Journal of Mathematics

In this paper, our aim is to study some properties of the tangent bundle with a deformed complete lift metric.


Pseudosymmetric Lightlike Hypersurfaces, Sema Kazan, Bayram Şahi̇n Jan 2014

Pseudosymmetric Lightlike Hypersurfaces, Sema Kazan, Bayram Şahi̇n

Turkish Journal of Mathematics

We study lightlike hypersurfaces of a semi-Riemannian manifold satisfying pseudosymmetry conditions. We give sufficient conditions for a lightlike hypersurface to be pseudosymmetric and show that there is a close relationship of the pseudosymmetry condition of a lightlike hypersurface and its integrable screen distribution. We obtain that a pseudosymmetric lightlike hypersurface is a semisymmetric lightlike hypersurface or totally geodesic under certain conditions. Moreover, we give an example of pseudosymmetric lightlike hypersurfaces and investigate pseudoparallel lightlike hypersurfaces. Furthermore, we introduce Ricci-pseudosymmetric lightlike hypersurfaces, obtain characterizations, and give an example for such hypersurfaces.


On 4-Dimensional Almost Para-Complex Pure-Walker Manifolds, Murat İşcan, Hi̇lmi̇ Sarsilmaz, Si̇bel Turanli Jan 2014

On 4-Dimensional Almost Para-Complex Pure-Walker Manifolds, Murat İşcan, Hi̇lmi̇ Sarsilmaz, Si̇bel Turanli

Turkish Journal of Mathematics

This paper is concerned with almost para-complex structures on Walker 4-manifolds. For these structures, we study some problems of Kähler manifolds. We also give an example of a flat almost para-complex manifold, which consists of a nonintegrable almost para-complex structure on Walker 4-manifolds.


On The Equivariant Cohomology Algebra For Solenoidal Actions, Ali̇ Arslan Özkurt Jan 2014

On The Equivariant Cohomology Algebra For Solenoidal Actions, Ali̇ Arslan Özkurt

Turkish Journal of Mathematics

We prove, under certain conditions, that if a solenoidal group (i.e. 1-dimensional compact connected abelian group) acts effectively on a compact space then the fixed point set is nonempty and H_G^*(X,Q) has a presentation similar to the presentation of H^*(X,Q) as proven by Chang in the case of a circle group.


Functionals Of Gasser--Muller Estimators, Petre Babilua, Elizbar Nadaraya, Grigol Sokhadze Jan 2014

Functionals Of Gasser--Muller Estimators, Petre Babilua, Elizbar Nadaraya, Grigol Sokhadze

Turkish Journal of Mathematics

The asymptotic properties of a general functional of the Gasser--Muller estimator are investigated in the Sobolev space. The convergence rate, consistency, and central limit theorem are established.


On Minimal Poincaré 4-Complexes, Alberto Cavicchioli, Friedrich Hegenbarth, Dusan Repovs Jan 2014

On Minimal Poincaré 4-Complexes, Alberto Cavicchioli, Friedrich Hegenbarth, Dusan Repovs

Turkish Journal of Mathematics

We consider 2 types of minimal Poincaré 4-complexes. One is defined with respect to the degree 1-map order. This idea was already present in our previous papers, and more systematically studied later by Hillman. The second type of minimal Poincaré 4-complexes was introduced by Hambleton, Kreck, and Teichner. It is not based on an order relation. In the present paper we study existence and uniqueness questions.


Coverings And Crossed Modules Of Topological Groups With Operations, Osman Mucuk, Tunçar Şahan Jan 2014

Coverings And Crossed Modules Of Topological Groups With Operations, Osman Mucuk, Tunçar Şahan

Turkish Journal of Mathematics

It is a well-known result of the covering groups that a subgroup G of the fundamental group at the identity of a semilocally simply connected topological group determines a covering morphism of topological groups with characteristic group G. In this paper we generalize this result to a large class of algebraic objects called topological groups with operations, including topological groups. We also prove that the crossed modules and internal categories within topological groups with operations are equivalent. This equivalence enables us to introduce the cover of crossed modules within topological groups with operations. Finally, we draw relations between the coverings …


Central Configurations In The Collinear 5-Body Problem, Muhammad Shoaib, Anoop Sivasankaran, Abdulrehman Kashif Jan 2014

Central Configurations In The Collinear 5-Body Problem, Muhammad Shoaib, Anoop Sivasankaran, Abdulrehman Kashif

Turkish Journal of Mathematics

We study the inverse problem of central configuration of collinear general 4- and 5-body problems. A central configuration for n-body problems is formed if the position vector of each particle with respect to the center of mass is a common scalar multiple of its acceleration. In the 3-body problem, it is always possible to find 3 positive masses for any given 3 collinear positions given that they are central. This is not possible for more than 4-body problems in general. We consider a collinear 5-body problem and identify regions in the phase space where it is possible to choose positive …


Hausdorff Dimension Of The Graph Of The Error-Sum Function Of \Alpha-Lüroth Series, Haibo Chen, Wenbo Wang, Min Yu Jan 2014

Hausdorff Dimension Of The Graph Of The Error-Sum Function Of \Alpha-Lüroth Series, Haibo Chen, Wenbo Wang, Min Yu

Turkish Journal of Mathematics

Let \alpha be a countable partition of the unit interval [0,1]. In this paper, we will introduce the error-sum function of \alpha-Lüroth series and determine the Hausdorff dimension of its graph when the partition \alpha is eventually decreasing. Some other properties of the error-sum function are also investigated.


On The Continued Fraction Expansion Of Some Hyperquadratic Functions, Khalil Ayadi, Fatma Taktak Jan 2014

On The Continued Fraction Expansion Of Some Hyperquadratic Functions, Khalil Ayadi, Fatma Taktak

Turkish Journal of Mathematics

In this paper, we consider continued fraction expansions for algebraic power series over a finite field. Especially, we are interested in studying the continued fraction expansion of a particular subset of algebraic power series over a finite field, called hyperquadratic. This subset contains irrational elements \alpha satisfying an equation \alpha = f(\alpha^r), where r is a power of the characteristic of the base field and f is a linear fractional transformation with polynomials coefficients. The continued fraction expansion for these elements can sometimes be given fully explicitly. We will show this expansion for hyperquadratic power series satisfying certain types of …


The New Method Of Determining Koebe Domains For The Class Of Typically Real Functions Under Montel's Normalization, Leopold Koczan, Pawel Zaprawa Jan 2014

The New Method Of Determining Koebe Domains For The Class Of Typically Real Functions Under Montel's Normalization, Leopold Koczan, Pawel Zaprawa

Turkish Journal of Mathematics

We consider the class T(r) of typically real functions with the normalization f(0)=0 and f(r)=r for a fixed r \in (0,1). In the limiting case, when r tends to 0, the class T(r) coincides with the class T of typically real functions normalized by f(0)=f'(0)-1=0. In 1980, Lewandowski and Miazga determined the Koebe domain for T(r), i.e. the set of the form \bigcap_{f\in T(r)} f(\Delta). They used the method applied earlier by Goodman. In this paper we present a new, complete method of determining this set. As a corollary, we obtain the Koebe set for T.


An Existence Result For A Quasilinear System With Gradient Term Under The Keller--Osserman Conditions, Dragos Patru Covei Jan 2014

An Existence Result For A Quasilinear System With Gradient Term Under The Keller--Osserman Conditions, Dragos Patru Covei

Turkish Journal of Mathematics

We use some new technical tools to obtain the existence of entire solutions for the quasilinear elliptic system of type \Delta _pu_i+h_i(\vert x\vert) \vert \nabla u_i\vert ^{p-1}=a_i(\vert x\vert ) f_i(u_{1},u_2) on R^N (N\geq 3, i=1,2) where N-1\geq p>1, \Delta_p is the p-Laplacian operator, and h_i, a_i, f_i are suitable functions. The results of this paper supplement the existing results in the literature and complete those obtained by Jesse D Peterson and Aihua W Wood (Large solutions to non-monotone semilinear elliptic systems, Journal of Mathematical Analysis and Applications, Volume 384, pages 284--292, 2011).


Osserman Lightlike Hypersurfaces Of Indefinite S-Manifolds, Letizia Brunetti Jan 2014

Osserman Lightlike Hypersurfaces Of Indefinite S-Manifolds, Letizia Brunetti

Turkish Journal of Mathematics

We mainly deal with the problem of admissibility for screen distributions on a lightlike hypersurface of both a semi-Riemannian manifold and an indefinite S-manifold. In the latter case, we first show that a characteristic screen distribution is never admissible, and then we provide a characterization for admissible screen distributions on proper totally umbilical lightlike hypersurfaces. Finally, in studying Osserman conditions, we characterize Osserman totally umbilical hypersurfaces of a semi-Riemannian manifold, obtaining explicit results on the eigenvalues of the pseudo-Jacobi operators in the case of lightlike hypersurfaces with Lorentzian screen leaves.


On The Size Of The Third Homotopy Group Of The Suspension Of An Eilenberg--Maclane Space, Peyman Niroomand, Francesco Russo Jan 2014

On The Size Of The Third Homotopy Group Of The Suspension Of An Eilenberg--Maclane Space, Peyman Niroomand, Francesco Russo

Turkish Journal of Mathematics

The nonabelian tensor square G \otimes G of a group G of G = p^n and G' = p^m (p prime and n,m \ge 1) satisfies a classic bound of the form G \otimes G \le p^{n(n-m)}. This allows us to give an upper bound for the order of the third homotopy group \pi_3(SK(G,1)) of the suspension of an Eilenberg--MacLane space K(G,1), because \pi_3(K(G,1)) is isomorphic to the kernel of \kappa : x \otimes y \in G \otimes G \mapsto [x,y] \in G'. We prove that G \otimes G \le p^{(n-1)(n-m)+2}, sharpening not only G \otimes G \le p^{n(n-m)} but …


Degenerate Hopf Bifurcations, Hidden Attractors, And Control In The Extended Sprott E System With Only One Stable Equilibrium, Zhouchao Wei, Irene Moroz, Anping Liu Jan 2014

Degenerate Hopf Bifurcations, Hidden Attractors, And Control In The Extended Sprott E System With Only One Stable Equilibrium, Zhouchao Wei, Irene Moroz, Anping Liu

Turkish Journal of Mathematics

In this paper, we introduce an extended Sprott E system by a general quadratic control scheme with 3 arbitrary parameters for the new system. The resulting system can exhibit codimension-one Hopf bifurcations as parameters vary. The control strategy used can be applied to create degenerate Hopf bifurcations at desired locations with preferred stability. A complex chaotic attractor with only one stable equilibrium is derived in the sense of having a positive largest Lyapunov exponent. The chaotic attractor with only one stable equilibrium can be generated via a period-doubling bifurcation. To further suppress chaos in the extended Sprott E system coexisting …


Continuity Of Wigner-Type Operators On Lorentz Spaces And Lorentz Mixed Normed Modulation Spaces, Ayşe Sandikçi Jan 2014

Continuity Of Wigner-Type Operators On Lorentz Spaces And Lorentz Mixed Normed Modulation Spaces, Ayşe Sandikçi

Turkish Journal of Mathematics

We study various continuity properties for \tau-Wigner transform on Lorentz spaces and \tau-Weyl operators W_{\tau}^{a} with symbols belonging to appropriate Lorentz spaces. We also study the action of \tau-Wigner transform on Lorentz mixed normed modulation spaces.


On Semiparallel Anti-Invariant Submanifolds Of Generalized Sasakian Space Forms, Ci̇han Özgür, Fatma Gürler, Cengi̇zhan Murathan Jan 2014

On Semiparallel Anti-Invariant Submanifolds Of Generalized Sasakian Space Forms, Ci̇han Özgür, Fatma Gürler, Cengi̇zhan Murathan

Turkish Journal of Mathematics

We consider minimal anti-invariant semiparallel submanifolds of generalized Sasakian space forms. We show that the submanifolds are totally geodesic under certain conditions.


Seiberg--Witten-Like Equations On 5-Dimensional Contact Metric Manifolds, Nedi̇m Deği̇rmenci̇, Şenay Bulut Jan 2014

Seiberg--Witten-Like Equations On 5-Dimensional Contact Metric Manifolds, Nedi̇m Deği̇rmenci̇, Şenay Bulut

Turkish Journal of Mathematics

In this paper, we write Seiberg--Witten-like equations on contact metric manifolds of dimension 5. Since any contact metric manifold has a Spin^c-structure, we use the generalized Tanaka--Webster connection on a Spin^c spinor bundle of a contact metric manifold to define the Dirac-type operators and write the Dirac equation. The self-duality of 2-forms needed for the curvature equation is defined by using the contact structure. These equations admit a nontrivial solution on 5-dimensional strictly pseudoconvex CR manifolds whose contact distribution has a negative constant scalar curvature.


Adjoints Of Rationally Induced Composition Operators On Bergman And Dirichlet Spaces, Aliakbar Goshabulaghi, Hamid Vaezi Jan 2014

Adjoints Of Rationally Induced Composition Operators On Bergman And Dirichlet Spaces, Aliakbar Goshabulaghi, Hamid Vaezi

Turkish Journal of Mathematics

We will state a connection between the adjoints of a vast variety of bounded operators on 2 different weighted Hardy spaces. We will apply it to determine the adjoints of rationally induced composition operators on Dirichlet and Bergman spaces.


Essential Norms Of Weighted Composition Operators Between Zygmund-Type Spaces And Bloch-Type Spaces, Amir Hossein Sanatpour, Mostafa Hassanlou Jan 2014

Essential Norms Of Weighted Composition Operators Between Zygmund-Type Spaces And Bloch-Type Spaces, Amir Hossein Sanatpour, Mostafa Hassanlou

Turkish Journal of Mathematics

We investigate the boundedness of weighted composition operator u C_{\varphi} mapping the Zygmund-type space Z^{\alpha} into the Bloch-type space B^{\beta}. Then we give essential norm estimates of such an operator in terms of u and \varphi.


General Rotational Surfaces In The 4-Dimensional Minkowski Space, Georgi Ganchev, Velichka Milousheva Jan 2014

General Rotational Surfaces In The 4-Dimensional Minkowski Space, Georgi Ganchev, Velichka Milousheva

Turkish Journal of Mathematics

General rotational surfaces as a source of examples of surfaces in the 4-dimensional Euclidean space were introduced by C. Moore. In this paper we consider the analogue of these surfaces in the Minkowski 4-space. On the basis of our invariant theory of spacelike surfaces we study general rotational surfaces with special invariants. We describe analytically the flat general rotational surfaces and the general rotational surfaces with flat normal connection. We classify completely the minimal general rotational surfaces and the general rotational surfaces consisting of parabolic points.