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Full-Text Articles in Physical Sciences and Mathematics

The Theory Of Jacobi Systems And Their Abelian Representations, M. Shahryari, Y. Zamani Jan 2004

The Theory Of Jacobi Systems And Their Abelian Representations, M. Shahryari, Y. Zamani

Turkish Journal of Mathematics

In this article we introduce a new generalization of the concept of Lie ring which we call Jacobi system and we investigate some elementary properties of these systems and their Abelian representations.


On The Power Subgroups Of The Extended Modular Group \Gamma, Recep Şahi̇n, Sebahatti̇n İki̇kardeş, Özden Koruoğlu Jan 2004

On The Power Subgroups Of The Extended Modular Group \Gamma, Recep Şahi̇n, Sebahatti̇n İki̇kardeş, Özden Koruoğlu

Turkish Journal of Mathematics

In this paper we describe the group structure of power subgroups \Gamma^m of the extended modular group \Gamma and the quotients to them. Then we give some relations between the power subgroups \Gamma^m, the commutator subgroups \Gamma^{\prime} and \Gamma^{\prime \prime} and also the information of interest about free normal subgroups of the extended modular group \Gamma.


Groups With Rank Restrictions On Non-Subnormal Subgroups, Leonid Andreevich Kurdachenko, Howard Smith Jan 2004

Groups With Rank Restrictions On Non-Subnormal Subgroups, Leonid Andreevich Kurdachenko, Howard Smith

Turkish Journal of Mathematics

Let G be a group in which every non-subnormal subgroup has finite rank. This paper considers the question as to which extra conditions on such a group G ensure that G has all subgroups subnormal. For example, if G is torsion-free and locally soluble-by-finite then either G has finite 0-rank or G is nilpotent. Several results are obtained on soluble (respectively, locally soluble-by-finite) groups satisfying the stated hypothesis on subgroups.


On Orthogonal Generalized Derivations Of Semiprime Rings, Nurcan Argaç, Atsushi Nakajima, Emi̇ne Albaş Jan 2004

On Orthogonal Generalized Derivations Of Semiprime Rings, Nurcan Argaç, Atsushi Nakajima, Emi̇ne Albaş

Turkish Journal of Mathematics

In this paper, we present some results concerning two generalized derivations on a semiprime ring. These results are a generalization of results of M. Bre\u{s}ar and J. Vukman in [2], which are related to a theorem of E. Posner for the product of derivations on a prime ring.


On Near-Rings With Two-Sided \Alpha-Derivations, Nurcan Argaç Jan 2004

On Near-Rings With Two-Sided \Alpha-Derivations, Nurcan Argaç

Turkish Journal of Mathematics

In this paper, we introduce the notion of two-sided \alpha-derivation of a near-ring and give some generalizations of [1]. Let N be a near ring. An additive mapping f: N\rightarrow N is called an { \it (\alpha, \beta)-derivation } if there exist functions \alpha,\beta : N\rightarrow N such that f(xy)=f(x)\alpha(y)+\beta (x)f(y) for all x,y\in N. An additive mapping d:N\rightarrow N is called a two-sided \alpha-derivation if d is an (\alpha,1)-derivation as well as a (1,\alpha)-derivation. The purpose of this paper is to prove the following two assertions: (i) Let N be a semiprime near-ring, I be a subset of N …


Ideal Theory In Topological Algebras, A. Najmi Jan 2004

Ideal Theory In Topological Algebras, A. Najmi

Turkish Journal of Mathematics

Given a simplicial topologically non radical algebra A, we characterize its topological radical, radA. If furthermore A is advertive, then radA coincides with the Jacobson radical RadA. On the other hand, it is shown that every two-sided invertive simplicial topological Gelfand-Mazur algebra has a functional spectrum and for every topologically nonradical simplicial Gelfand-Mazur amits the set \mathcal{X}(A), of all continuous multiplicative linear functionals, is not empty.


On Simultaneous Approximation By A Linear Combination Of A New Sequence Of Linear Positive Operators, P. N. Agrawal, Ali J. Mohammad Jan 2004

On Simultaneous Approximation By A Linear Combination Of A New Sequence Of Linear Positive Operators, P. N. Agrawal, Ali J. Mohammad

Turkish Journal of Mathematics

In [1] we introduced a new sequence of linear positive operators M_{n} to approximate unbounded continuous functions of exponential growth on [0,\infty). As this sequence is saturated with O(n^{-1}), to accelerate the rate of convergence we applied the technique of linear combination introduced by May [3] and Rathore et al. [4] to these operators. The object of the present paper is to study the phenomena of simultaneous approximation (approximation of derivatives of functions by the corresponding order derivatives of operators) by the linear combination M_{n} ( . , k, x) of M_{n}. First, we establish a Voronovskaja-type asymptotic formula and …


F-Invariant Submanifolds Of Kaehlerian Product Manifold, Mehmet Atçeken Jan 2004

F-Invariant Submanifolds Of Kaehlerian Product Manifold, Mehmet Atçeken

Turkish Journal of Mathematics

In this paper, the geometry of F-invariant submanifolds of a Kaehlerian product manifold is studied. The fundamental properties of these submanifolds are investigated such as pseudo umbilical, curvature invariant, totally geodesic, mixed geodesic submanifold and locally decomposable Riemannian product manifold.


On Local Hörmander-Beurling Spaces, Jairo Villegas Jan 2004

On Local Hörmander-Beurling Spaces, Jairo Villegas

Turkish Journal of Mathematics

In this paper we aim to extend a result of Hörmander's, that \mathcal{B}_{p,k}^{loc}(\Omega)\subset\mathcal{C}^m(\Omega) if \frac{(1+\left \cdot\right )^m}{k}\in L_{p^\prime}, to the setting of vector valued local Hörmander-Beurling spaces, as well as to show that the space \bigcap_{j=1}^\infty\mathcal{B}_{p_j,k_j}^{loc} (\Omega, E) (1\leq p_j\leq\infty, k_j=e^{j\omega}, j=1,2,\dots) is topologically isomorphic to \mathcal{E}_\omega(\Omega, E ). Moreover, it is well known that the union of Sobolev spaces \mathcal{H}_{s}^{loc}(\Omega) (=\mathcal{B}_{2,(1+ \cdot ^2)^{s/2}}^{loc}(\Omega)) coincides with the space \mathcal{D}^{\prime\,F}(\Omega) of finite order distributions on \Omega. We show that this is also verified in the context of vector valued Beurling ultradistributions.


On \Theta-Euclidean L-Fuzzy Ideals Of Rings, Ayten Koç, Erol Balkanay Jan 2004

On \Theta-Euclidean L-Fuzzy Ideals Of Rings, Ayten Koç, Erol Balkanay

Turkish Journal of Mathematics

In this paper we define a \theta-Euclidean level subset and a \theta-Euclidean level ideal. We also give some properties of a \theta-Euclidean level subset.


New Special Curves And Developable Surfaces, Shyuichi Izumiya, Nobuko Takeuchi Jan 2004

New Special Curves And Developable Surfaces, Shyuichi Izumiya, Nobuko Takeuchi

Turkish Journal of Mathematics

We define new special curves in Euclidean 3-space which we call slant helices and conical geodesic curves. Those notions are generalizations of the notion of cylindrical helices. One of the results in this paper gives a classification of special developable surfaces under the condition of the existence of such a special curve as a geodesic. As a result, we consider geometric invariants of space curves. By using these invariants, we can estimate the order of contact with those special curves for general space curves. All arguments in this paper are straight forward and classical. However, there have been no papers …


Galois Symmetry On Floer Cohomology, Kenji Fukaya Jan 2003

Galois Symmetry On Floer Cohomology, Kenji Fukaya

Turkish Journal of Mathematics

In this article, we define an action of \hat{\Bbb Z} on the A_{\infty} category whose objects are rational Lagrangian submanifolds together with some other data. The group \hat{\Bbb Z} is a Galois group of the (universal) Novikov ring (field) over Laurent polynomial field. By mirror symmetry it will corresponds to the algebraic fundamental group of a punctured disk which parametrize the maximal degenerate family of the mirror complex manifold.


A Monopole Homology For Integral Homology 3-Spheres, Weiping Li Jan 2003

A Monopole Homology For Integral Homology 3-Spheres, Weiping Li

Turkish Journal of Mathematics

To an integral homology 3-sphere Y, we assign a well-defined {\mathbb Z}-graded (monopole) homology MH_*(Y, I_{\eta}(\Theta; \eta_0)) whose construction in principle follows from the instanton Floer theory with the dependence of the spectral flow I_{\eta}(\Theta; \eta_0), where \Theta is the unique U(1)-reducible monopole of the Seiberg-Witten equation on Y and \eta_0 is a reference perturbation datum. The definition uses the moduli space of monopoles on Y \times {\mathbb R} introduced by Seiberg-Witten in studying smooth 4-manifolds. We show that the monopole homology MH_*(Y, I_{\eta}(\Theta; \eta_0)) is invariant among Riemannian metrics with same I_{\eta}(\Theta; \eta_0). This provides a chamber-like structure for …


Adjunction Inequality And Coverings Of Stein Surfaces, Stefan Nemirovski Jan 2003

Adjunction Inequality And Coverings Of Stein Surfaces, Stefan Nemirovski

Turkish Journal of Mathematics

A stronger form of the adjunction inequality is proved for immersed real surfaces in non simply-connected Stein surfaces. The result is applied to the geometry of Stein domains and analytic continuation on complex surfaces.


Groups Whose Proper Subgroups Are Hypercentral Of Length At Most \Leq \Omega, Selami̇ Ercan Jan 2003

Groups Whose Proper Subgroups Are Hypercentral Of Length At Most \Leq \Omega, Selami̇ Ercan

Turkish Journal of Mathematics

Groups, all proper subgroups of which are hypercentral of length at most \omega and every proper subgroup of which is a B_{n}-group for a natural number n depending on the subgroup, are studied in this article.


On Invariant Submanifolds Of Riemannian Warped Product Manifold, Mehmet Atçeken, Bayram Şahi̇n, Erol Kiliç Jan 2003

On Invariant Submanifolds Of Riemannian Warped Product Manifold, Mehmet Atçeken, Bayram Şahi̇n, Erol Kiliç

Turkish Journal of Mathematics

In this paper, we generalize the geometry of the invariant submanifolds of Riemannian product manifold to the geometry of the invariant submanifolds of Riemannian warped product manifold. We investigate some properties of an invariant submanifolds of a Riemannian warped product manifold. We show that every invariant submanifold of the Riemannian warped product manifold is a Riemannian warped product manifold. Also, we give a theorem on the pseudo-umbilical invariant submanifold. Further, we obtain that integral manifolds on an invariant submanifold are curvature-invariant submanifolds. Finally, we give a necessary condititon on a totally umbilical invariant submanifold to be totally geodesic.


Uniqueness Of Primary Decompositions, Patrick F. Smith Jan 2003

Uniqueness Of Primary Decompositions, Patrick F. Smith

Turkish Journal of Mathematics

Uniqueness properties of primary decompositions in modules over non-commutative rings are presented.


On Some Properties Of Szasz-Mirakyan Operators In Hölder Spaces, Zbigniew Walczak, Lucyna Rempulska Jan 2003

On Some Properties Of Szasz-Mirakyan Operators In Hölder Spaces, Zbigniew Walczak, Lucyna Rempulska

Turkish Journal of Mathematics

We study some properties of modified Szasz-Mirakyan operators in Hölder exponential weighted spaces. We give theorems on the degree of approximation of functions by these operators.


Pushouts Of Profinite Crossed Modules And Cat^1-Profinite Groups, Murat Alp, Özgün Gürmen Jan 2003

Pushouts Of Profinite Crossed Modules And Cat^1-Profinite Groups, Murat Alp, Özgün Gürmen

Turkish Journal of Mathematics

In this paper, we presented a brief review of crossed modules [7], cat^1-groups [6], pullback crossed modules [4], pullback cat^1-group [1], profinite crossed modules [5], cat^1-profinite groups [5], pullback profinite crossed modules [5], pullback cat^1-profinite groups [3]. We defined the pushout cat^1-profinite groups and gave the left adjoint constructions.


On Prime Submodules Of Finitely Generated Free Modules, Di̇lek Pusat Yilmaz Jan 2003

On Prime Submodules Of Finitely Generated Free Modules, Di̇lek Pusat Yilmaz

Turkish Journal of Mathematics

The aim of this work is to investigate prime submodules of finitely generated free modules over commutative domains in some special cases.


Fiber Sums Of Genus 2 Lefschetz Fibrations, Denis Auroux Jan 2003

Fiber Sums Of Genus 2 Lefschetz Fibrations, Denis Auroux

Turkish Journal of Mathematics

Using the recent results of Siebert and Tian about the holomorphicity of genus 2 Lefschetz fibrations with irreducible singular fibers, we show that any genus 2 Lefschetz fibration becomes holomorphic after fiber sum with a holomorphic fibration.


On Cofinite Subgroups Of Mapping Class Groups, Mustafa Korkmaz Jan 2003

On Cofinite Subgroups Of Mapping Class Groups, Mustafa Korkmaz

Turkish Journal of Mathematics

For every positive integer n, we exhibit a cofinite subgroup \Gamma_n of the mapping class group of a surface of genus at most two such that \Gamma_n admits an epimorphism onto a free group of rank n. We conclude that H^1 (\Gamma_n; {\mathbb Z}) has rank at least n and the dimension of the second bounded cohomology of each of these mapping class groups is the cardinality of the continuum. In the case of genus two, the groups \Gamma_n can be chosen not to contain the Torelli group. Similarly for hyperelliptic mapping class groups. We also exhibit an automorphism of …


Comparing Open Book And Heegaard Decompositions Of 3-Manifolds, J. Hyam Rubinstein Jan 2003

Comparing Open Book And Heegaard Decompositions Of 3-Manifolds, J. Hyam Rubinstein

Turkish Journal of Mathematics

We study the maximal value of the Euler characteristic of the pages of all open book decompositions of closed orientable 3-manifolds. In particular, we describe some examples where the minimal genus Heegaard splittings of such 3-manifolds give rise to open book decompositions and other examples where the simplest open book decomposition has larger maximal Euler characteristic of pages than the smallest genus Heegaard splittings. Also, special properties of the Heegaard splitting associated to an open book decomposition are given. Techniques of minimal surface theory and hyperbolic geometry are shown to be useful for such problems.


Some Asymptotic Results For The Semi-Markovian Random Walk With A Special Barrier, Tahi̇r Khani̇yev Jan 2003

Some Asymptotic Results For The Semi-Markovian Random Walk With A Special Barrier, Tahi̇r Khani̇yev

Turkish Journal of Mathematics

In this study, the semi-Markovian random walk with a special barrier (X(t)) is considered and under some weak assumptions the ergodicity of this process is discussed. Moreover, the characteristic function of ergodic distribution of X(t) is given by using a joint distribution of random variables N and Y_{N} and some exact formulas for the first and second moments of ergodic distribution of the process X(t) are obtained. Based on these results, the asymptotic behaviours of expectation and variance of this process are investigated as S-s \to \infty . It is finally proved that the ergodic distribution of the process is …


Boundary Points Of Self-Affine Sets In R, İbrahi̇m Kirat Jan 2003

Boundary Points Of Self-Affine Sets In R, İbrahi̇m Kirat

Turkish Journal of Mathematics

Let A be an n \times n expanding matrix with integer entries and D = \{0, d_1, ... , d_{N-1} \} \subseteq {\Bbb{Z}}^n be a set of N distinct vectors, called an N-digit set. The unique non-empty compact set T = T(A,D) satisfying AT = T + D is called a self-affine set. If T has positive Lebesgue measure, it is called a self-affine region. In general, it is not clear how to determine a point to be on the boundary of a self-affine region. In this note, we consider one-dimensional self-affine regions T and present a simple approach to …


On Lightlike Hypersurfaces Of A Semi-Riemannian Space Form, Rifat Güneş, Bayram Şahi̇n, Erol Kiliç Jan 2003

On Lightlike Hypersurfaces Of A Semi-Riemannian Space Form, Rifat Güneş, Bayram Şahi̇n, Erol Kiliç

Turkish Journal of Mathematics

In this paper, we study a Lightlike hypersurface of a semi-Riemann manifold. We show that a lightlike hypersurface is totally geodesic if and only if it is locally symmetric. Also, we show that a lightlike Hypersurface of IR_{4q}^{4m}(m,q > 1) is totally geodesic under some restrictions. Finally, we give some results on Ricci curvature of a lightlike hypersurface to be symmetric.


On Pseudohyperbolical Curves In Minkowski Space-Time, Çeti̇n Camci, Kazim İlarslan, Emilija Sucurovic Jan 2003

On Pseudohyperbolical Curves In Minkowski Space-Time, Çeti̇n Camci, Kazim İlarslan, Emilija Sucurovic

Turkish Journal of Mathematics

In this paper, we characterize all spacelike, timelike and null curves lying on the pseudohyperbolic space H_0^3 in the Minkowski space--time E_1^4. Moreover, we prove that there are no timelike and no null curves lying on the pseudohyperbolic space H_0^3 in Minkowski space--time E_1^4.


Automorphism Groups Of (M-1)-Surfaces With The M-Property, Adnan Melekoğlu Jan 2003

Automorphism Groups Of (M-1)-Surfaces With The M-Property, Adnan Melekoğlu

Turkish Journal of Mathematics

A compact Riemann surface X of genus g is called an (M-1)-surface if it admits an anticonformal involution that fixes g simple closed curves, the second maximum number by Harnack's theorem. If X also admits an automorphism of order g which cyclically permutes these g curves, then we shall call X an (M-1)-surface with the M-property. In this paper we investigate the automorphism groups of (M-1)-surfaces with the M-property.


On Intuitionistic Fuzzy Subhypernear-Rings Of Hypernear-Rings, Kyung Ho Kim Jan 2003

On Intuitionistic Fuzzy Subhypernear-Rings Of Hypernear-Rings, Kyung Ho Kim

Turkish Journal of Mathematics

In this paper, we introduce the concept of an intuitionistic fuzzy subhypernear-ring of a hypernear-ring and obtain some results in this connection.


Professor Masatoshi Gündüz Ikeda: A Life Devoted To Mathematics, Cemal Koç Jan 2003

Professor Masatoshi Gündüz Ikeda: A Life Devoted To Mathematics, Cemal Koç

Turkish Journal of Mathematics

No abstract provided.