Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 90

Full-Text Articles in Physical Sciences and Mathematics

Homological Dimensions Of Complexes Related To Cotorsion Pairs, Chongqing Wei, Limin Wang, Husheng Qiao Jan 2014

Homological Dimensions Of Complexes Related To Cotorsion Pairs, Chongqing Wei, Limin Wang, Husheng Qiao

Turkish Journal of Mathematics

Let (A, B) be a cotorsion pair in R-Mod. We define and study notions of A dimension and B dimension of unbounded complexes, which is given by means of dg-projective resolution and dg-injective resolution, respectively. As an application, we extend the Gorenstein flat dimension of complexes, which was defined by Iacob. Gorenstein cotorsion, FP-projective, FP-injective, Ding projective, and Ding injective dimension are also extended from modules to complexes. Moreover, we characterize Noetherian rings, von Neumann regular rings, and QF rings by the FP-projective, FP-injective, and Ding projective (injective) dimension of complexes, respectively.


Highly Nonconcurrent Longest Paths And Cycles In Lattices, Yasir Bashir Jan 2014

Highly Nonconcurrent Longest Paths And Cycles In Lattices, Yasir Bashir

Turkish Journal of Mathematics

We investigate here the connected graphs with the property that any pair of vertices are missed by some longest paths (or cycles), embeddable in n-dimensional lattices L^n where L denotes the set of integers.


On Transformations Of Index 1, Leyla Bugay, Osman Kelekci̇ Jan 2014

On Transformations Of Index 1, Leyla Bugay, Osman Kelekci̇

Turkish Journal of Mathematics

The index and the period of an element a of a finite semigroup are defined as the smallest values of m \geq 1 and r \geq 1 such that a^{m+r}=a^m, respectively. If m=1 then a is called an element of index 1. The aim of this paper is to find some properties of the elements of index 1 in T_n, which we call transformations of index 1.


Horizontally Submersions Of Contact Cr-Submanifolds, Fortune Massamba, Tshikunguila Tshikuna-Matamba Jan 2014

Horizontally Submersions Of Contact Cr-Submanifolds, Fortune Massamba, Tshikunguila Tshikuna-Matamba

Turkish Journal of Mathematics

In this paper, we discuss some geometric properties of almost contact metric submersions involving symplectic manifolds. We show that the structures of quasi-K-cosymplectic and quasi-Kenmotsu manifolds are related to (1, 2)-symplectic structures. For horizontally submersions of contact CR-submanifolds of quasi-K-cosymplectic and quasi-Kenmotsu manifolds, we study the principal characteristics and prove that their total spaces are CR-product. Curvature properties between curvatures of quasi-K-cosymplectic and quasi-Kenmotsu manifolds and the base spaces of such submersions are also established. We finally prove that, under a certain condition, the contact CR-submanifold of a quasi Kenmotsu manifold is locally a product of a totally geodesic leaf …


Coloring Hypercomplete And Hyperpath Graphs, Yusuf Ci̇van, Demet Taylan Jan 2014

Coloring Hypercomplete And Hyperpath Graphs, Yusuf Ci̇van, Demet Taylan

Turkish Journal of Mathematics

Given a graph G with an induced subgraph H and a family F of graphs, we introduce a (hyper)graph H_H(G;F)=(V_H, E_H), the hyper-H (hyper)graph of G with respect to F, whose vertices are induced copies of H in G, and \{H_1,H_2,\ldots,H_r\} \in E_H if and only if the induced subgraph of G by the set \cup_{i=1}^r H_i is isomorphic to a graph F in the family F, and the integer r is the least integer for F with this property. When H is a k-complete or a k-path of G, we abbreviate H_{K_k}(G;F) and H_{P_k}(G;F) to H_k(G;F) and HP_k(G;F), respectively. …


Euler-Seidel Matrices Over F_P, Nesri̇n Tutaş Jan 2014

Euler-Seidel Matrices Over F_P, Nesri̇n Tutaş

Turkish Journal of Mathematics

A Euler--Seidel matrix is determined by an infinite sequence whose elements are given by recursion. The recurrence relations are investigated for numbers and polynomials such as hyperharmonics, Lucas numbers, and Euler and Genocchi polynomials. Linear recurring sequences in finite fields are employed, for instance, in coding theory and in several branches of electrical engineering. In this work, we define the period of a Euler--Seidel matrix over a field F_p with p elements, where p is a prime number. We give some results for the matrix whose initial sequence is \{s_r(n)\}_{n=0}^{\infty}, where s_r(n)=\sum_{k=0}^n {\binom{n}{k}}^r, n \geq 0, and r is a …


On Betti Series Of The Universal Modules Of Second Order Derivations Of \Frac{K[X_1,X_2,...,X_S]}{(F)}, Ali̇ Erdoğan, Hali̇se Meli̇s Teki̇n Akçi̇n Jan 2014

On Betti Series Of The Universal Modules Of Second Order Derivations Of \Frac{K[X_1,X_2,...,X_S]}{(F)}, Ali̇ Erdoğan, Hali̇se Meli̇s Teki̇n Akçi̇n

Turkish Journal of Mathematics

Let R be a coordinate ring of an affine irreducible curve represented by \frac{k[x_1,x_2,...,x_s]}{(f)} and m be a maximal ideal of R. In this article, the Betti series of \Omega_2(R_m) is studied. We proved that the Betti series of \Omega_2(R_m), where \Omega_2(R_m) denotes the universal module of second order derivations of R_m, is a rational function under some conditions.


Some Results On T-Noncosingular Modules, Rachid Tribak Jan 2014

Some Results On T-Noncosingular Modules, Rachid Tribak

Turkish Journal of Mathematics

The notion of T-noncosingularity of a module has been introduced and studied recently. In this article, a number of new results of this property are provided. It is shown that over a commutative semilocal ring R such that Jac(R) is a nil ideal, every T-noncosingular module is semisimple. We prove that for a perfect ring R, the class of T-noncosingular modules is closed under direct sums if and only if R is a primary decomposable ring. Finitely generated T-noncosingular modules over commutative rings are shown to be precisely those having zero Jacobson radical. We also show that for a simple …


A Class Of Uniquely (Strongly) Clean Rings, Orhan Gürgün, Ayşe Çi̇ğdem Özcan Jan 2014

A Class Of Uniquely (Strongly) Clean Rings, Orhan Gürgün, Ayşe Çi̇ğdem Özcan

Turkish Journal of Mathematics

In this paper we call a ring R \delta_r-clean if every element is the sum of an idempotent and an element in \delta(R_R) where \delta(R_R) is the intersection of all essential maximal right ideals of R. If this representation is unique (and the elements commute) for every element we call the ring uniquely (strongly) \delta_r-clean. Various basic characterizations and properties of these rings are proved, and many extensions are investigated and many examples are given. In particular, we see that the class of \delta_r-clean rings lies between the class of uniquely clean rings and the class of exchange rings, and …


On The Structure Of Some Modules Over Generalized Soluble Groups, Leonid Andreevich Kurdachenko, Igor Yakov Subbotin, Vasiliy Anatolievich Chupordya Jan 2014

On The Structure Of Some Modules Over Generalized Soluble Groups, Leonid Andreevich Kurdachenko, Igor Yakov Subbotin, Vasiliy Anatolievich Chupordya

Turkish Journal of Mathematics

Let R be a ring and G a group. An R-module A is said to be Artinian-by-(finite rank) if Tor_R(A) is Artinian and A/ Tor_R(A) has finite R-rank. We study a module A over a group ring RG such that A/C_A(H) is Artinian-by-(finite rank) (as an R-module) for every proper subgroup H.


On 2 Nonsplit Extension Groups Associated With Hs And Hs:2, Jamshid Moori, Thekiso Seretlo Jan 2014

On 2 Nonsplit Extension Groups Associated With Hs And Hs:2, Jamshid Moori, Thekiso Seretlo

Turkish Journal of Mathematics

The group HS:2 is the full automorphism group of the Higman--Sims group HS. The groups 2^{4.}S_6 and 2^{5.}S_6 are maximal subgroups of HS and HS:2, respectively. The group 2^{4.}S_6 is of order 11520 and 2^{5.}S_6 is of order 23040 and each of them is of index 3 850 in HS and HS:2, respectively. The aim of this paper is to first construct \overline{G} = 2^{5.}S_6 as a group of the form 2^{4.}S_6.2 (that is, \overline{G} = G_1.2) and then compute the character tables of these 2 nonsplit extension groups by using the method of Fischer--Clifford theory. We will show that …


On Finsler Metrics With Vanishing S-Curvature, Akbar Tayebi, Hassan Sadeghi, Esmaeil Peyghan Jan 2014

On Finsler Metrics With Vanishing S-Curvature, Akbar Tayebi, Hassan Sadeghi, Esmaeil Peyghan

Turkish Journal of Mathematics

In this paper, we consider Finsler metrics defined by a Riemannian metric and a 1-form on a manifold. We study these metrics with vanishing S-curvature. We find some conditions under which such a Finsler metric is Berwaldian or locally Minkowskian.


Conformally Parallel Spin(7) Structures On Solvmanifolds, Selman Uğuz Jan 2014

Conformally Parallel Spin(7) Structures On Solvmanifolds, Selman Uğuz

Turkish Journal of Mathematics

In this paper we review the Spin(7) geometry in relation to solvmanifolds. Starting from a 7-dimensional nilpotent Lie group N endowed with an invariant G_2 structure, we present an example of a homogeneous conformally parallel Spin(7) metric on an associated solvmanifold. It is thought that this paper could lead to very interesting and exciting areas of research and new results in the direction of (locally conformally) parallel Spin(7) structures.


Geometry Of Almost Cliffordian Manifolds: Classes Of Subordinated Connections, Jaroslav Hrdina, Petr Vasik Jan 2014

Geometry Of Almost Cliffordian Manifolds: Classes Of Subordinated Connections, Jaroslav Hrdina, Petr Vasik

Turkish Journal of Mathematics

An almost Clifford and an almost Cliffordian manifold is a G--structure based on the definition of Clifford algebras. An almost Clifford manifold based on O:= Cl (s,t) is given by a reduction of the structure group GL(km, R) to GL(m, O), where k=2^{s+t} and m \in N. An almost Cliffordian manifold is given by a reduction of the structure group to GL(m, O) GL(1, O). We prove that an almost Clifford manifold based on O is such that there exists a unique subordinated connection, while the case of an almost Cliffordian manifold based on O is more rich. A class …


Generalized Derivations On Jordan Ideals In Prime Rings, Mahmoud El-Soufi, Ahmed Aboubakr Jan 2014

Generalized Derivations On Jordan Ideals In Prime Rings, Mahmoud El-Soufi, Ahmed Aboubakr

Turkish Journal of Mathematics

Let R be a 2-torsion free prime ring with center Z(R), J be a nonzero Jordan ideal also a subring of R, and F be a generalized derivation with associated derivation d. In the present paper, we shall show that J\subseteq Z(R) if any one of the following properties holds: (i) [F(u), u]\in Z(R), (ii) F(u)u = ud(u), (iii) d(u^2)=2F(u)u, (iv) F(u^2)-2uF(u) = d(u^2)-2ud(u), (v) F^2(u)+3d^2(u)=2Fd(u)+2dF(u), (vi) F(u^2) = 2uF(u) for all u \in J.


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).


Pullback Diagram Of H^*-Algebras, Mahnaz Khanehgir, Maryam Amyari, Marzieh Moradian Khibary Jan 2014

Pullback Diagram Of H^*-Algebras, Mahnaz Khanehgir, Maryam Amyari, Marzieh Moradian Khibary

Turkish Journal of Mathematics

In this paper we obtain some properties for the pullback diagram of H^*-algebras. More precisely, we prove that the commutative diagram of H^*-algebras and morphisms A_1 @>\varphi_1>> B_1 @VV\psi_1V @VV\psi_2V A_2 @>\varphi_2>> B_2 is pullback and \psi_1 is an injection if and only if \psi_1 is a surjection, \psi_2 is an injection, and \ker \varphi_1 \cap \ker \psi_1 = \{0\}.


Relaxed Elastic Line In A Riemannian Manifold, Gözde Özkan, Ahmet Yücesan Jan 2014

Relaxed Elastic Line In A Riemannian Manifold, Gözde Özkan, Ahmet Yücesan

Turkish Journal of Mathematics

We obtain a differential equation with 2 boundary conditions for a relaxed elastic line in a Riemannian manifold. This differential equation, which is found with respect to constant sectional curvature G, geodesic curvature \kappa, and 2 boundary conditions, gives a more direct and more geometric approach to questions concerning a relaxed elastic line in a Riemannian manifold. We give various theorems and results in terms of a relaxed elastic line. Consequently, we examine the concept of a relaxed elastic line in 2- and 3- dimensional space forms.


Almost Contact Metric Submersions And Symplectic Manifolds, Augustin Batubenge, Tshikunguila Tshikuna-Matamba Jan 2014

Almost Contact Metric Submersions And Symplectic Manifolds, Augustin Batubenge, Tshikunguila Tshikuna-Matamba

Turkish Journal of Mathematics

In this paper, we discuss some geometric properties of almost contact metric submersions involving symplectic manifolds. We show that this is obtained if the total space is an b-almost Kenmotsu manifold.


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).


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.


Counting Pseudo-Anosov Mapping Classes On The 3-Punctured Projective Plane, Blazej Szepietowski Jan 2014

Counting Pseudo-Anosov Mapping Classes On The 3-Punctured Projective Plane, Blazej Szepietowski

Turkish Journal of Mathematics

We prove that in the pure mapping class group of the 3-punctured projective plane equipped with the word metric induced by certain generating set, the ratio of the number of pseudo-Anosov elements to the number of all elements in a ball centered at the identity tends to one, as the radius of the ball tends to infinity. We also compute growth functions of the sets of reducible and pseudo-Anosov elements.


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.


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 …


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.


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.


On Direct Products Of S-Posets Satisfying Flatness Properties, Roghaieh Khosravi Jan 2014

On Direct Products Of S-Posets Satisfying Flatness Properties, Roghaieh Khosravi

Turkish Journal of Mathematics

In this paper we characterize pomonoids over which various flatness properties of S-posets are preserved under direct products.


Global Existence, Uniform Decay, And Exponential Growth Of Solutions For A System Of Viscoelastic Petrovsky Equations, Faramarz Tahamtani, Amir Peyravi Jan 2014

Global Existence, Uniform Decay, And Exponential Growth Of Solutions For A System Of Viscoelastic Petrovsky Equations, Faramarz Tahamtani, Amir Peyravi

Turkish Journal of Mathematics

In this paper, we study the initial-boundary value problem for a system of nonlinear viscoelastic Petrovsky equations. Introducing suitable perturbed energy functionals and using the potential well method we prove uniform decay of solution energy under some restrictions on the initial data and the relaxation functions. Moreover, we establish a growth result for certain solutions with positive initial energy.


Scattering Data In An Inverse Scattering Problem On The Semi-Axis For A First-Order Hyperbolic System, Mansur Ismailov, İbrahi̇m Teki̇n Jan 2014

Scattering Data In An Inverse Scattering Problem On The Semi-Axis For A First-Order Hyperbolic System, Mansur Ismailov, İbrahi̇m Teki̇n

Turkish Journal of Mathematics

The inverse scattering problem for the first-order hyperbolic system on the semi-axis in the case of 2 incident and 2 scattered waves under consideration of 2 problems with the same given incident waves and different boundary conditions is considered. The scattering data on the semi-axis are given in terms of the scattering operator on the whole axis for the same system with the coefficients, which are extended in the whole axis by zero.