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Full-Text Articles in Mathematics

Immersions Preserved Under Rotations With Totally Reducible Focal Set, Rıdvan Ezentaş Jan 1997

Immersions Preserved Under Rotations With Totally Reducible Focal Set, Rıdvan Ezentaş

Turkish Journal of Mathematics

In [1] Carter and the author introduced the idea of an immersion f : Mm-+ Rn with totally reducible focal set (TRFS). Such an immersion has the property that, for all p E M, the focal set with base p is a union of hyperplanes in the normal plane to f(M) at f(p) . Here we show that if we take two immersions with TRFS then we can construct new immersions with TRFS. In particular, rotating an immersion with TRFS about an axis gives anew immersion with TRFS.


Quotients Of Real Algebraic Sets Via Finite Groups, Yıldıray Ozan Jan 1997

Quotients Of Real Algebraic Sets Via Finite Groups, Yıldıray Ozan

Turkish Journal of Mathematics

In this paper, we will study finite algebraic group actions on real algebraic sets and compare the topological quotient X/G with the algebraic quotient X/ /G. We will give a different and shorter proof of a result of Procesi and Schwarz, stating that if the order of the group G, acting algebraically on a real algebraic set X, is odd then X/G is equal to X/ /G. In the case of even order groups, we will a give sufficient condition ( and a necessary condition in the case G = Z_2 ) for the X / G to be equal …


Locally Nilpotent P-Groups Whose Proper Subgroups Are Nc-Groups, A.O. Asar, A. Yalincaklioğlu Jan 1997

Locally Nilpotent P-Groups Whose Proper Subgroups Are Nc-Groups, A.O. Asar, A. Yalincaklioğlu

Turkish Journal of Mathematics

Let G be a locally nilpotent p-group in which every proper subgroup is an NC-group. It is shown that G is itself an NC-group if either (i) the normal closure of every finite subgroup of G is a Chernikov extension of a CC-group or (ii) every proper normal subgroup of G is the union of an ascending chain of normal CCsubgroups.


Weight Equations For Binary Linear Codes And Their Applications, Ersan Akyildiz, İsmai̇l Ş. Güloğlu, Masatoshi Ikeda Jan 1997

Weight Equations For Binary Linear Codes And Their Applications, Ersan Akyildiz, İsmai̇l Ş. Güloğlu, Masatoshi Ikeda

Turkish Journal of Mathematics

Some combinatorial problems concerning binary vector spaces are solved by applying the techniques developed in [1]. These illustrate that they are effective tools for such purposes.


Some New Sequence Spaces Defined By A Sequence Of Moduli, Ayhan Esi̇ Jan 1997

Some New Sequence Spaces Defined By A Sequence Of Moduli, Ayhan Esi̇

Turkish Journal of Mathematics

In this paper we introduce and exaamine some properties of three sequence spaces defined by using a sequence of moduli.


Locally Finite Barely Transitive Permutation Group With Almost Nilpotent Point Stabilizers, Mahmut Kuzucuoğlu Jan 1997

Locally Finite Barely Transitive Permutation Group With Almost Nilpotent Point Stabilizers, Mahmut Kuzucuoğlu

Turkish Journal of Mathematics

We show that the groups mentioned in the title are solvable. Moreover, a point stabilizer H of the locally finite barely transitive group G is almost nilpotent, whenever the indices H : H \cap H^g (g \in G) have a finite upper bound.


On Univalent Functions With Three Preassigend Values, Y. Avci, E. Zlotkiewicz Jan 1997

On Univalent Functions With Three Preassigend Values, Y. Avci, E. Zlotkiewicz

Turkish Journal of Mathematics

In this paper, univalent functions with three preassigend values are studied. The sharp bounds for the first coefficient are obtained. Moreover, the coefficient problem for a subclass of such functions is completely solved.


On High Order Riesz Transformations Generated By Generalized Shift Operator, İsmai̇l Eki̇nci̇oğlu, İ. Kaya Özkin Jan 1997

On High Order Riesz Transformations Generated By Generalized Shift Operator, İsmai̇l Eki̇nci̇oğlu, İ. Kaya Özkin

Turkish Journal of Mathematics

In this paper, we determine high order Riesz transformations by using generalized shift operators and giving some of their properties.


The Rank And The Crank Modulo 5, A. Bülent Eki̇n Jan 1997

The Rank And The Crank Modulo 5, A. Bülent Eki̇n

Turkish Journal of Mathematics

Let p(n) denote the number of partitions of n . Ramanujan's partition congruences are p(5n + 4) , p(7n + 5) and p(11n + 6) = mod 5, 7, and 11, respectively. These have been proved in number of ways. Atkin and Swinnerton-Dyer proved the congruences and some more relations about partition İn the case of mod5 and 7 in terms of rank, Garvan proved them in three cases in terms of crank. In this study, we give an another proof of their results in the case of mod5 by using the theory of modular forms. Although our method is …


About Some Normal Subgroups Of Hecke Groups, İsmail Naci Cangül Jan 1997

About Some Normal Subgroups Of Hecke Groups, İsmail Naci Cangül

Turkish Journal of Mathematics

In this work we study the suucture of some special normal subgroups of Hecke groups. Particwarly those of genus O and 1 are studied by means of the regwar map theory which has been a growing subject in recent years. As a nice application, we calcwate the total number of genus 1 normal subgroups for a given index.


Application Of The Residue Method To A Mixed Problem, Y. A. Mamedov, M. Can Jan 1996

Application Of The Residue Method To A Mixed Problem, Y. A. Mamedov, M. Can

Turkish Journal of Mathematics

In this paper, the residue method of separation of variables is applied to a mixed problem which includes the flow of a stratified compresslble fluid and inner gravitational waves of a stratified incompressible fluid for special values of the coefficients of the equation. To apply this method one defines two auxiliary problems. The first one is a spectral problem and the second is a Cauchy problem. Using the solutions of auxiliary problems, an existence and uniqueness theorem is proved for the given mixed problem.


Products And Quotients Of (P,\Sigma)-Absolutely Continuous Operator Ideals^*, Enrique A. Sanchez Perez Jan 1996

Products And Quotients Of (P,\Sigma)-Absolutely Continuous Operator Ideals^*, Enrique A. Sanchez Perez

Turkish Journal of Mathematics

We obtain a generalization of the ideal {\cal M}_{(q,p)} of (q,p)-mixing operators-in the sense of Pietsch- as a consequence of the study of the quotients of (p, \sigma)-absolutely continuous operator ideals {\cal P}_{p, \sigma} -in the sense of Jarchow and Matter-. Inclusions {\cal P}_{p, \sigma} (E,F) \subset {\cal M}_{(q,s)} (E,F) are also investigated, specially for the cases E={\cal C}(K) and E=L_1.


On Surjectivity Of The Arens Homomorphism, S. Alpay, B. Turan Jan 1996

On Surjectivity Of The Arens Homomorphism, S. Alpay, B. Turan

Turkish Journal of Mathematics

We define approximate separation and extension properties of a Banach lattice and study the relation between these and topological fullness of the ideal centre. Banach lattices with topologically full ideal centre are characterized as those for which the Arens homomorphism m: Z(E)''\rightarrow Z(E') is surjective. Among the positive operators T:E\rightarrow F between Banach lattices E,F we distinguish nearly Z(E) and Z(F) extremal ones and study their properties.


Certain Classes Of Analytic And Multivalent Functions With Negative Coefficients, M. K. Aouf, A. Shamandy, A.A. Attiyia Jan 1996

Certain Classes Of Analytic And Multivalent Functions With Negative Coefficients, M. K. Aouf, A. Shamandy, A.A. Attiyia

Turkish Journal of Mathematics

We introduce a subclass K^{*}_{n+p-1}(A,B) of analytic and p-valent functions with negative coefficients. Coefficient estimates, some properties, distortion theorems and closure theorems of functions belonging to the class K^{*}_{n+p-1}(A,B) are determined. Also we obtain radii of close-to-convexity, starlikeness and convexity for the class K^{*}_{n+p-1}(A,B). We also obtain class preserving integral operator of the form F(z)=\frac{c+p}{z^c}\int_0^{z}t^{c-1}f(t) dt, c> -p for the class K^{*}_{n+p-1}(A,B) Conversely when F(z)\,\, \in K_{n+p-1}^{\star} (A,B) radius of p-valence of f(z) defined by the above equation is obtained.


Weak Forms Of Openness Based Upon Denseness, C. W. Baker Jan 1996

Weak Forms Of Openness Based Upon Denseness, C. W. Baker

Turkish Journal of Mathematics

A function is defined to be hardly open provided that the inverse image of each dense subset of the codomain that is contained in a proper open set is dense in the domain. This form of weak openness is shown to be strictly between near feeble openness and somewhat openness. Characterizations and properties of hardly open functions are presented.


Suborbital Graphs For The Normalizer Of\Gamma_O(N), M. Akbaş, T. Başkan Jan 1996

Suborbital Graphs For The Normalizer Of\Gamma_O(N), M. Akbaş, T. Başkan

Turkish Journal of Mathematics

In this paper we examine some properties of suborbital graphs for the normalizer {\cal N} of \Gamma_{0}(N) in PSL(2,R) and show that, if {\cal N}/\Gamma_{0}(N) and the set of orbit representatives are denoted by B and \Omega respectively, the permutation group (B,\Omega) is regular and m-regular where m is an odd natural number.


On Homogeneous Riemann Boundary Value Problem, K. Kutlu Jan 1996

On Homogeneous Riemann Boundary Value Problem, K. Kutlu

Turkish Journal of Mathematics

In this work we consider homogeneous Riemann boundary value problem (BVP) on general open rectifiable curves. We prove certain estimates for Cauchy type integrals in terms of local moduli of continuity and local maximum of modulus, which allow us to describe the solvability of Riemann BVP with unbounded oscillating coefficients on a wide class of non-smooth rectifiable Jordan curves.


On Strongly Regular Rings, A. Kaya, F. Kuzucuoğlu Jan 1996

On Strongly Regular Rings, A. Kaya, F. Kuzucuoğlu

Turkish Journal of Mathematics

Some characterizations of strongly regular rings will be given. Let R be a ring and I(\neq R) a right ideal of R. If, for each pair of right ideals A and B of R, AB \subseteq I implies that either A \subseteq I or B \subseteq I, then I is called a prime right ideal (or equivalently, if aRb \ \ \not\subseteq I whenever a and b do not belong to I). I is strongly prime right ideal if, for each pair of a and b in R, aIb \subseteq I and ab \in I imply that either a \in …


Weak\Star- Invariantly Complemented Subspaces Of L^{\Infty}(1/\Omega) And Ideals Of L^{1}(\Omega) With A Bounded Approximate Identity, Z. Argün, C. Tonyali Jan 1996

Weak\Star- Invariantly Complemented Subspaces Of L^{\Infty}(1/\Omega) And Ideals Of L^{1}(\Omega) With A Bounded Approximate Identity, Z. Argün, C. Tonyali

Turkish Journal of Mathematics

For a locally compact group G let L^{1}(\omega) be the weighted group algebra and let X be a weak \star-closed translation invariant subspace of L^{\infty} (1/\omega). In this paper for a certain class of functions we show that the following conditions are equivalent: (i) X is topological invariantly complemented in L^{\infty}(1/\omega); (ii) X is invariantly complemented in L^{\infty}(1/\omega); (iii) The left ideal X_{\perp} has a bounded right approximate identity.


Extension Of Caristi-Kirk's Theorem, M. O. Diallo, M. Oudadess Jan 1996

Extension Of Caristi-Kirk's Theorem, M. O. Diallo, M. Oudadess

Turkish Journal of Mathematics

We give some extensions and/or improvements, to uniform spaces and to multi-valued mappings, of Caristi-Kirk's theorem.


Normal Boundary Value Problems For Differential Equations Of Higher Order, F. G. Maksudov, Z. I. Ismailov Jan 1996

Normal Boundary Value Problems For Differential Equations Of Higher Order, F. G. Maksudov, Z. I. Ismailov

Turkish Journal of Mathematics

In this work the arbitrary order differential operator expression of the form \imath (u) = \frac{\partial u (t)}{\partial t^n}+Au(t), where A is a bounded normal operator in the Hilbert Space H is considered in the Hilbert Space of vector functions L_2(H(0,1)). This paper describes all normal boundary value problem for the indicated diferential expression in terms of abstnract boundary conditions and determines a connection with other typea of boundary value problems.


T_2-Objects In Categories Of Filter And Local Filter Convergence Spaces, M. Baran Jan 1996

T_2-Objects In Categories Of Filter And Local Filter Convergence Spaces, M. Baran

Turkish Journal of Mathematics

There are various generalizations of the usual T_2 (Hausdorff) axiom of topology to an arbitrary topological category defined in [1]. In this paper, four more new generalizations of Hausdorff spaces are given in the topological categories. Moreover, the relationships among all of these T_2 structures and the ones given in [5] and [7] as well as some invariance properties of them are investigated in the categories of filter and local filter convergence spaces. Keywords: Topological Categories, T_2-objects, Filter Convergence Spaces.


On Conformally Flat Lorentzian Spaces Satisfying A Certain Condition On The Curvature Tensor, M. Erdoğan Jan 1996

On Conformally Flat Lorentzian Spaces Satisfying A Certain Condition On The Curvature Tensor, M. Erdoğan

Turkish Journal of Mathematics

In this paper we prove a local classification theorem for the conformally flat lorentzian spaces satisfying the condition R(X,Y)R=0.


On The Additive Group Structure Of Nonstandard Models Of Z, Ç. Gencer, M. Terzi̇ler Jan 1996

On The Additive Group Structure Of Nonstandard Models Of Z, Ç. Gencer, M. Terzi̇ler

Turkish Journal of Mathematics

Let \hat{Z} denote the inverse limit of finite cyclic groups and F_gZ the group where $F$ is a vector space over Q and + is defined by (a, x)+(b, y)=(a+b, x+y+g(a,b)) for some g: F\times F\rightarrow Z. In this paper we show that any nonstandard model Z^{\star} of Z is isomorphic to F_{\beta}Z for some \beta: F\rightarrow \hat{Z} where F=Z^{\star}/Z.


A Note On Double Sequences Of Fuzzy Numbers, E. Savaş Jan 1996

A Note On Double Sequences Of Fuzzy Numbers, E. Savaş

Turkish Journal of Mathematics

In this paper we introduce double convergent sequences of fuzzy numbers and we also study the space of double convergent sequences of fuzzy numbers.


Rings In Which Strongly Prime Right Ideals Are Finitely Generated, A. Kaya Jan 1996

Rings In Which Strongly Prime Right Ideals Are Finitely Generated, A. Kaya

Turkish Journal of Mathematics

Some properties of rings in which every strongly prime right ideal is finitely generated will be investigated, and sufficient conditions for such rings to be right noetherian will be given. Let R be an s-unital ring (i.e., a\in aR\cap Ra for each a\in R) and I(\neq R)a right ideal of R. If, for each right ideals A and B of R, AB\subseteq I implies that either A\subseteq I or B\subseteq I, then I is called a prime right ideal (or equivalently, if a\, R\,b \not\subseteq I whenever a and b do not belong to I). I is strongly prime if, …


A Property Of Meldrum Groups, A. O. Asar, S. Atlihan Jan 1996

A Property Of Meldrum Groups, A. O. Asar, S. Atlihan

Turkish Journal of Mathematics

In this work it is shown that the direct product of two Meldrum groups does not satisfy the normalizer condition. It is not known yet if the same result holds true for any two HM-groups.


The Group Structure Of Hecke Groups H(\Lambda_Q), İ. N. Cangül Jan 1996

The Group Structure Of Hecke Groups H(\Lambda_Q), İ. N. Cangül

Turkish Journal of Mathematics

In this work a new proof of the fact that the group structure of the Hecke groups is isomorphic to the free product of two cyclic groups of orders 2 and q is given The method used in the proof requires a result of A.M. Macbeath together with the notion of fundamental region. Also given are some new results on the parabolic points of Hecke groups, which still is an open problem.


Absolutely Representing Systems And Convolution Operators In The Complex Domain, Yu. F. Korobeinik Jan 1996

Absolutely Representing Systems And Convolution Operators In The Complex Domain, Yu. F. Korobeinik

Turkish Journal of Mathematics

The author suggests a method of characterizing of the kernel of a convolution-type operator. The method is based on the exact description of nontrivial expansions of zero of an absolutely representing system consisting of eigen vectors of some linear operator with continuous spectrum. The method suggested in the paper is applied to the characterization of the kernel of the convolution-type operator defined on some space of entire functions and to the factorization of such an operator.


(\Sigma, \Tau)- Lie Ideals In Prime Rings With Derivation, M. Soytürk Jan 1996

(\Sigma, \Tau)- Lie Ideals In Prime Rings With Derivation, M. Soytürk

Turkish Journal of Mathematics

Let R be a prime ring, char R\neq 2,3 \, \sigma, \tau : R\rightarrow R two automorphisms, U a nonzero (\sigma, \tau)- Lie ideal of R and o\neq d : R\rightarrow R$ a derivation such that \sigma d = d\sigma, \tau d = d\tau. In this paper we have proved the following results. (1) If d (U) \subset Z then U\subset Z (2) If d(U) \subset U and d^2 (U) \subset Z then U\subset Z.