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Full-Text Articles in Physical Sciences and Mathematics

Solving Fuzzy Linear Programming Problems With Linear Membership Function, Rafail R. Gasimov, Kürşat Yeni̇lmez Jan 2002

Solving Fuzzy Linear Programming Problems With Linear Membership Function, Rafail R. Gasimov, Kürşat Yeni̇lmez

Turkish Journal of Mathematics

In this paper, we concentrate on two kinds of fuzzy linear programming problems: linear programming problems with only fuzzy technological coefficients and linear programming problems in which both the right-hand side and the technological coefficients are fuzzy numbers. We consider here only the case of fuzzy numbers with linear membership functions. The symmetric method of Bellman and Zadeh [2] is used for a defuzzification of these problems. The crisp problems obtained after the defuzzification are non-linear and even non-convex in general. We propose here the ``modified subgradient method'' and use it for solving these problems. We also compare the new …


Numerical Solution And Convergence Speed Of Variational Formulation For Linear Schrödinger Equation, Murat Subaşi, Bünyami̇n Yildiz Jan 2002

Numerical Solution And Convergence Speed Of Variational Formulation For Linear Schrödinger Equation, Murat Subaşi, Bünyami̇n Yildiz

Turkish Journal of Mathematics

This paper presents a numerical solution of an optimal control problem for linear parabolic equations. The estimates for the error of the difference scheme and the speed of convergence have been established. Numerical results are reported on test problems.


Field Extensions Having The Unique Subfield Property, And G-Cogalois Extensions, Toma Albu Jan 2002

Field Extensions Having The Unique Subfield Property, And G-Cogalois Extensions, Toma Albu

Turkish Journal of Mathematics

We present a short proof, based on Cogalois Theory, of a result due to Acosta de Orozco and Vélez (1982, J. Number Theory 15, 388-405) characterizing separable simple radical field extensions with the unique subfield property, and prove that these extensions are precisely the simple G--Cogalois extensions with a cyclic Kneser group.


Ko-Groups Of Bounded Flag Manifolds, Yusuf Ci̇van Jan 2002

Ko-Groups Of Bounded Flag Manifolds, Yusuf Ci̇van

Turkish Journal of Mathematics

We exhibit an appropriate suspension of bounded flag manifolds as a wedge sum of Thom complexes of associated complex line bundles. We use the existence of such a splitting to assist our computation of real and complex K-groups. Moreover, we compute the Sq^2-homology of bounded flag manifolds to make use of relevant Atiyah-Hirzebruch spectral sequence of KO-theory.


On Summand Sum And Summand Intersection Property Of Modules, Mustafa Alkan, Abdullah Harmanci Jan 2002

On Summand Sum And Summand Intersection Property Of Modules, Mustafa Alkan, Abdullah Harmanci

Turkish Journal of Mathematics

R will be an associative ring with identity and modules M will be unital left R- modules. In this work, extending modules and lifting modules with the SSP (or SIP) are studied. A necessary and sufficient condition for a module M to have the SSP is that for every decomposition M = A\oplus B and f\in Hom(A,B), Im(f) is a direct summand of B. Among others it is shown also that a (C_3) module with the SIP has the SSP, and a (D_3) module with SSP has the SIP.


\Theta-Euclidean L-Fuzzy Ideals Of Rings, Ayten Koç, Erol Balkanay Jan 2002

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

Turkish Journal of Mathematics

The concept of fuzzy ideals is extended by introducing \theta -Euclidean L-fuzzy ideals in rings. In particular, some structural theorems for a \theta -Euclidean L-fuzzy ideal of R are proved.


Left Adjoint Of Pullback Cat^1- Profinite Groups, Murat Alp Jan 2002

Left Adjoint Of Pullback Cat^1- Profinite Groups, Murat Alp

Turkish Journal of Mathematics

In this paper, we present a brief review crossed modules \cite{whitehead}, cat^1-groups \cite{loday}, profinite crossed modules \cite{kortim}, cat^1-profinite groups \cite{kortim}, pullback profinite crossed modules \cite{kortim} and also the pullback cat^1- profinite groups \cite{hind}. We prove that the pulback cat^1-profinite group has a left adjoint which is the induced cat^1-group.


New Tensor Norms And Operator Ideals Associated To Interpolation Spaces Between Sequence Spaces, G. Castaneda, J. A. Lopez Molina, M. J. Rivera Jan 2002

New Tensor Norms And Operator Ideals Associated To Interpolation Spaces Between Sequence Spaces, G. Castaneda, J. A. Lopez Molina, M. J. Rivera

Turkish Journal of Mathematics

We introduce a wide class of tensor norms g_{\lambda,\rho} which are defined with the help of interpolation spaces between perfect sequence spaces defined by a general parameter real interpolation method. We also characterize the associated \lambda_{\rho}-nuclear and \lambda_{\rho}-integral operators.


Characterizations Of Artinian And Noetherian Gamma-Rings In Terms Of Fuzzy Ideals, Mehmet Ali̇ Öztürk, Mustafa Uçkun, Young Bae Jun Jan 2002

Characterizations Of Artinian And Noetherian Gamma-Rings In Terms Of Fuzzy Ideals, Mehmet Ali̇ Öztürk, Mustafa Uçkun, Young Bae Jun

Turkish Journal of Mathematics

Using fuzzy ideals, characterizations of Noetherian \Gamma-rings are given, and a condition for a \Gamma-ring to be Artinian is also given.


On Non-Existence Of Korovkin's Theorem In The Space Of L_{P}-Locally Integrable Functions, A. D. Gadjiev, Ertan İbi̇kli̇ Jan 2002

On Non-Existence Of Korovkin's Theorem In The Space Of L_{P}-Locally Integrable Functions, A. D. Gadjiev, Ertan İbi̇kli̇

Turkish Journal of Mathematics

It is shown that a Korovkin-type theorem does not hold in the weighted space of L_{p}-locally integrable functions on the whole real axis.


Asymptotic Formulas For The Eigenvalues Of The Schrodinger Operator, Şi̇ri̇n Atilgan, Sedef Karakiliç, Oktay A. Veliev Jan 2002

Asymptotic Formulas For The Eigenvalues Of The Schrodinger Operator, Şi̇ri̇n Atilgan, Sedef Karakiliç, Oktay A. Veliev

Turkish Journal of Mathematics

In this paper, we obtain asymptotic formulas for the eigenvalues of the d-dimensional Schrodinger operator L=-\Delta +q(x) in d-dimensional parallelepiped F with Dirichlet and Neumann boundary conditions.


Remarks On Bounded Operators In Köthe Spaces, P. B. Djakov, T. Terzi̇oğlu, M. Yurdakul, V. P. Zahariuta Jan 2002

Remarks On Bounded Operators In Köthe Spaces, P. B. Djakov, T. Terzi̇oğlu, M. Yurdakul, V. P. Zahariuta

Turkish Journal of Mathematics

We prove that if \lambda(A),\lambda(B) and \lambda(C) are Köthe spaces such that L(\lambda(A),\lambda(B)) and L(\lambda(C),\lambda(A)) consist of bounded operators then each operator acting on \lambda(A) that factors over \lambda(B)\widehat\otimes_{\pi} \lambda(C) is bounded.


Deformation Inequivalent Complex Conjugated Complex Structures And Applications, Viatcheslav Kharlamov, Viktor Kulikov Jan 2002

Deformation Inequivalent Complex Conjugated Complex Structures And Applications, Viatcheslav Kharlamov, Viktor Kulikov

Turkish Journal of Mathematics

We start from a short summary of our principal result from [KK]: an example of a complex algebraic surface which is not deformation equivalent to its complex conjugate and which, moreover, has no homeomorphisms reversing the canonical class. Then, we generalize this result to higher dimensions and construct several series of higher dimensional compact complex manifolds having no homeomorphisms reversing the canonical class. After that, we resume and broaden the applications given in [KK] and [KK2], in particular, as a new application, we propose examples of (deformation) non equivalent symplectic structures with opposite canonical classes.


Combinatorial Patchworking Of Real Pseudo-Holomorphic Curves, Ilia Itenberg, Eugenii Shustin Jan 2002

Combinatorial Patchworking Of Real Pseudo-Holomorphic Curves, Ilia Itenberg, Eugenii Shustin

Turkish Journal of Mathematics

The Viro method of construction of real algebraic varieties with prescribed topology uses convex subdivisions of Newton polyhedra. We show that in the case of arbitrary (not necessarily convex) subdivisions of polygons corresponding to C P^2 and rational ruled surfaces \Sigma_a, a \geq 0 the Viro method produces pseudo-holomorphic curves. The version of the Viro method discussed in the paper also gives a possibility to construct singular pseudo-holomorphic curves by gluing singular algebraic curves whose collections of singularities do not permit to glue these curves in the framework of the standard Viro method. As an application, we construct a series …


On 1-Point Gromov-Witten Invariants Of The Hilbert Schemes Of Points On Surfaces, Wei-Ping Li, Zhenbo Qin Jan 2002

On 1-Point Gromov-Witten Invariants Of The Hilbert Schemes Of Points On Surfaces, Wei-Ping Li, Zhenbo Qin

Turkish Journal of Mathematics

We compute certain 1-point genus-0 Gromov-Witten invariants of the Hilbert scheme of points on a simply-connected smooth projective surface.


Evidence For A Conjecture Of Pandharipande, Jim Bryan Jan 2002

Evidence For A Conjecture Of Pandharipande, Jim Bryan

Turkish Journal of Mathematics

In his paper ``Hodge integrals and degenerate contributions'', Pandharipande studied the relationship between the enumerative geometry of certain 3-folds and the Gromov-Witten invariants. In some good cases, enumerative invariants (which are manifestly integers) can be expressed as a rational combination of Gromov-Witten invariants. Pandharipande speculated that the same combination of invariants should yield integers even when they do not have any enumerative significance on the 3-fold. In the case when the 3-fold is the product of a complex surface and an elliptic curve, Pandharipande has computed this combination of invariants on the 3-fold in terms of the Gromov-Witten invariants of …


Minimality Of Certain Normal Connected Sums, Tian-Jun Li, Andras I. Stipsicz Jan 2002

Minimality Of Certain Normal Connected Sums, Tian-Jun Li, Andras I. Stipsicz

Turkish Journal of Mathematics

We show that the normal connected sum of two minimal symplectic 4-manifolds (neither of them rational or ruled) is a minimal symplectic 4-manifold. In the proof we use a symplectic sum formula for Gromov-Witten invariants.


Variations On Fintushel-Stern Knot Surgery On 4-Manifolds, Selman Akbulut Jan 2002

Variations On Fintushel-Stern Knot Surgery On 4-Manifolds, Selman Akbulut

Turkish Journal of Mathematics

We discuss some consequences Fintushel-Stern `knot surgery' operation coming from its handlebody description. We give some generalizations of this operation and give a counterexample to their conjecture.


Braids And Symplectic Four-Manifolds With Abelian Fundamental Group, Paul Seidel Jan 2002

Braids And Symplectic Four-Manifolds With Abelian Fundamental Group, Paul Seidel

Turkish Journal of Mathematics

We explain how a version of Floer homology can be used as an invariant of symplectic manifolds with b_1>0. As a concrete example, we look at four-manifolds produced from braids by a surgery construction. The outcome shows that the invariant is nontrivial; however, it is an open question whether it is stronger than the known ones.


Low-Dimensional Homology Groups Of Mapping Class Groups: A Survey, Mustafa Korkmaz Jan 2002

Low-Dimensional Homology Groups Of Mapping Class Groups: A Survey, Mustafa Korkmaz

Turkish Journal of Mathematics

In this survey paper, we give a complete list of known results on the first and the second homology groups of surface mapping class groups. Some known results on higher (co) homology are also mentioned.


Gauge Theory And Stein Fillings Of Certain 3-Manifolds, Andras I. Stipsicz Jan 2002

Gauge Theory And Stein Fillings Of Certain 3-Manifolds, Andras I. Stipsicz

Turkish Journal of Mathematics

In the following we show that a Stein filling S of the 3-torus T^3 is homeomorphic to D^2 \times T^2. In the proof we also show that if S is Stein and \partial S is diffeomorphic to the Seifert fibered 3-manifold -\Sigma (2,3,11) then b_1(S)=0 and Q_S=H. Similar results are obtained for the Poincaré homology sphere \pm \Sigma (2,3,5); in studying these fillings we apply recent gauge theoretic results, and prove our theorems by determining certain Seiberg-Witten invariants.


C-Closed Sets In L-Fuzzy Topological Spaces And Some Of Its Applications, Ali̇ Ahmed Nouh Jan 2002

C-Closed Sets In L-Fuzzy Topological Spaces And Some Of Its Applications, Ali̇ Ahmed Nouh

Turkish Journal of Mathematics

We introduce and study the notion of C-closed sets in L-fuzzy topological spaces. Then, C-convergence theory for nets and ideals is established in terms of C-closedness. Finally, we give a new concept of C-continuity on L-fuzzy topological space by means of L-fuzzy C-closedness and investigate some of its properties and its relationships with other L-fuzzy mappings introduced previously. Then we systematically study the characterizations of this notion with the aid of the C-convergence of L-fuzzy nets and L-fuzzy ideals.


Flat Marcinkiewicz Integral Operators, Hussain Al-Qassem, Ahmad Al-Salman Jan 2002

Flat Marcinkiewicz Integral Operators, Hussain Al-Qassem, Ahmad Al-Salman

Turkish Journal of Mathematics

In this paper, we study Marcinkiewicz integral operators with rough kernels supported by surfaces of revolutions. We prove that our operators are bounded on L^p under certain convexity assumptions on our surfaces and under very weak conditions on the kernel.


N-Commutator Groups, A. A. Mehrvarz, K. Azizi Jan 2002

N-Commutator Groups, A. A. Mehrvarz, K. Azizi

Turkish Journal of Mathematics

A sufficient condition such that any element of G' (the commutator subgroup of G) can be represented as a product of n commutators, was studied in \cite{GAL62}. In this article we study a necessary and sufficient condition such that any element of G' can be represented as a product of n commutators, Let n be the smallest nature number such that any element of finite group G can be represented as a product of n commutators. A group G with this property will be called an n -commutator group, and n will be denoted by c(G) . Then \frac{\ln( G' …


On Locally Pre-C^{*}-Algebra Structures In Locally M-Convex H^{*}-Algebras, A. El-Kinani Jan 2002

On Locally Pre-C^{*}-Algebra Structures In Locally M-Convex H^{*}-Algebras, A. El-Kinani

Turkish Journal of Mathematics

We endow any locally m-convex H^{*}-algebra \left( E,\tau \right) with a locally pre-C^{*}-topology weaker than \tau. Examples and applications are provided.


The Fine Spectra Of The Rhaly Operators On C_{0}, Mustafa Yildirim Jan 2002

The Fine Spectra Of The Rhaly Operators On C_{0}, Mustafa Yildirim

Turkish Journal of Mathematics

In 1975, Wenger [3] determined the fine spectra of Cesàro operator C_{1} on c, the space of convergent sequences. In [6], the spectrum of the Rhaly operators on c_{0} and c, under the assumption that {\displaystyle\lim_{n \rightarrow \infty}(n+1)a_{n} }=L\neq 0, has been determined. This paper presents the fine spectra of the Rhaly matrix R_{a} as an operator on the space c_{0}, with the same assumption.


On Derivations Of Prime Gamma Rings, Mehmet Ali̇ Öztürk, Young Bae Jun, Kyung Ho Kim Jan 2002

On Derivations Of Prime Gamma Rings, Mehmet Ali̇ Öztürk, Young Bae Jun, Kyung Ho Kim

Turkish Journal of Mathematics

We consider some results in a \Gamma-ring M with derivation which is related to Q, and the quotient \Gamma-ring of M.


On Some Properties Connecting Infinite Series, B. K. Lahiri, Pratulananda Das Jan 2002

On Some Properties Connecting Infinite Series, B. K. Lahiri, Pratulananda Das

Turkish Journal of Mathematics

We prove several theorems connecting infinite series of real terms in relation to Borel and Baire classification of sets and functions, connectedness of mappings, porosity character of sets etc.


Asymptotic Analysis Of Singularly Perturbed Abstract Evolution Equations In Banach And Hilbert Spaces, Dialla Konate Jan 2002

Asymptotic Analysis Of Singularly Perturbed Abstract Evolution Equations In Banach And Hilbert Spaces, Dialla Konate

Turkish Journal of Mathematics

In the current paper, we are concerned with the study of abstract linear evolution equations in Banach spaces in which the time derivative term is multiplied by a small parameter, say \epsilon. Such equations arise in the study of radiative transfer and neutron transport in Nuclear Physics. Following works by Krein (cf [9]) and others, Mika (cf [12,13,14,15]) using either the Hilbert method or the Compressed method has shown that the solution of the given singularly perturbed equation may be approximated upto any prescibed order by a sum of two asymptotic expansions that are the outer expansion that is valid …


On The Spectral Properties Of The Regular Sturm-Liouville Problem With The Lag Argument For Which Its Boundary Conditions Depends On The Spectral Parameter, Mehmet Bayramoğlu, Kevser Özden Köklü, Oya Baykal Jan 2002

On The Spectral Properties Of The Regular Sturm-Liouville Problem With The Lag Argument For Which Its Boundary Conditions Depends On The Spectral Parameter, Mehmet Bayramoğlu, Kevser Özden Köklü, Oya Baykal

Turkish Journal of Mathematics

In this paper, the asymptotic expression of the eigenvalues and eigenfunctions of the Sturm-Liouville equation with the lag argument y''(t) + \lambda^2 y(t) + M(t)y (t - \Delta(t)) = 0 and the spectral parameter in the boundary conditions \lambda y(0) +y'(0) = 0 \lambda^{2}y(\pi) + y'(\pi) = 0 y(t - \Delta(t)) = y(0)\varphi(t - \Delta(t)), t - \Delta(t) < 0 has been founded in a finite interval, where M(t) and \Delta(t) \geq 0 are continuous functions on [0, \pi], \lambda > 0 is a real parameter, \varphi(t) is an initial function which is satisfied with the condition \varphi(0) = 1 and continuous in the initial set.