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- Exchange rings (2)
- Oscillation (2)
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- C^*-extreme point (1)
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Articles 1 - 30 of 56
Full-Text Articles in Physical Sciences and Mathematics
Approximate Groups Iii: The Unitary Case, Emmanuel Breuillard, Ben Green
Approximate Groups Iii: The Unitary Case, Emmanuel Breuillard, Ben Green
Turkish Journal of Mathematics
By adapting the classical proof of Jordan's theorem on finite subgroups of linear groups, we show that every approximate subgroup of the unitary group U_n(C) is almost abelian.
Groupoids, Imaginaries And Internal Covers, Ehud Hrushovski
Groupoids, Imaginaries And Internal Covers, Ehud Hrushovski
Turkish Journal of Mathematics
Let T be a first-order theory. A correspondence is established between internal covers of models of T and definable groupoids within T. We also consider amalgamations of independent diagrams of algebraically closed substructures, and find strong relation between covers, uniqueness for 3-amalgamation, existence of 4-amalgamation, imaginaries of T^\si, and definable groupoids. As a corollary, we describe the imaginary elements of families of finite-dimensional vector spaces over pseudo-finite fields.
On Some New Inequalities For Convex Functions, Mevlüt Tunç
On Some New Inequalities For Convex Functions, Mevlüt Tunç
Turkish Journal of Mathematics
In the present paper we establish some new integral inequalities analogous to the well known Hadamard's inequality by using a fairly elementary analysis.
A Generalization Of Banach's Contraction Principle For Some Non-Obviously Contractive Operators In A Cone Metric Space, Yingxin Guo
Turkish Journal of Mathematics
This paper investigates the fixed points for self-maps of a closed set in a space of abstract continuous functions. Our main results essentially extend and generalize some fixed point theorems in cone metric spaces. An application to differential equations is given.
Geodesicity And Isoclinity Properties For The Tangent Bundle Of The Heisenberg Manifold With Sasaki Metric, Simona Luiza Druta, Paola Piu
Geodesicity And Isoclinity Properties For The Tangent Bundle Of The Heisenberg Manifold With Sasaki Metric, Simona Luiza Druta, Paola Piu
Turkish Journal of Mathematics
We prove that the horizontal and vertical distributions of the tangent bundle with the Sasaki metric are isocline, the distributions given by the kernels of the horizontal and vertical lifts of the contact form \omega on the Heisenberg manifold (H_3,g) to (TH_3,g^S) are not totally geodesic, and the distributions F^H=L(E_1^H,E_2^H) and F^V=L(E_1^V,E_2^V) are totally geodesic, but they are not isocline. We obtain that the horizontal and natural lifts of the curves from the Heisenberg manifold (H_3,g), are geodesics on the tangent bundle endowed with the Sasaki metric (TH_3,g^s), if and only if the curves considered on the base manifold are …
Weight And Nonlinearity Of Boolean Functions, Lavinia Corina Ciungu
Weight And Nonlinearity Of Boolean Functions, Lavinia Corina Ciungu
Turkish Journal of Mathematics
In this paper we analyze the weight and the nonlinearity of various types of Boolean functions. We give some general results related to rotation symmetric Boolean functions, and in particular, we prove partially a conjecture stated by Cusick and Stanica in [3].
Extensions And S-Comparability Of Exchange Rings, Chaoling Huang
Extensions And S-Comparability Of Exchange Rings, Chaoling Huang
Turkish Journal of Mathematics
Let S be a ring extension of R. In this note, for any positive integer s we study s-comparability related to ring extensions. We show that if S is an excellent extension of R, R and S are exchange rings, and R has the n-unperforation property. R satisfies s-comparability if and we only if so does S, and we prove that for a 2-sided ideal J of S, and an exchange subring R of the exchange ring S, which contains J as a direct summand, then R satisfies s-comparability if and only if so does R/J.
On Similarity Of Powers Of Shift Operators, Masoumeh Faghih Ahmadi, Karim Hedayatian
On Similarity Of Powers Of Shift Operators, Masoumeh Faghih Ahmadi, Karim Hedayatian
Turkish Journal of Mathematics
Let M_z and B denote, respectively, the multiplication operator and the backward shift operator on a weighted Hardy space. We present sufficient conditions so that M_{z^n} is similar to \bigoplus_1^nM_z, and B^n is similar to \bigoplus_1^nB. The first part generalizes a result obtained by Yucheng Li.
Best Constants In Second-Order Sobolev Inequalities On Compact Riemannian Manifolds In The Presence Of Symmetries, Mohammed Ali
Best Constants In Second-Order Sobolev Inequalities On Compact Riemannian Manifolds In The Presence Of Symmetries, Mohammed Ali
Turkish Journal of Mathematics
Let (M,g) be a smooth compact 3\leq n-dimensional Riemannian manifold, and G a subgroup of the isometry group of (M,g). We establish the best constants in second-order for a Sobolev inequality when the functions are G-invariant.
Pointwise Slant Submanifolds In Almost Hermitian Manifolds, Bang-Yen Chen, Oscar J. Garay
Pointwise Slant Submanifolds In Almost Hermitian Manifolds, Bang-Yen Chen, Oscar J. Garay
Turkish Journal of Mathematics
An interesting class of submanifolds of almost Hermitian manifolds (\tilde M,\tilde g,J) is the class of slant submanifolds. Slant submanifolds were introduced by the first author in [6] as submanifolds M of (\tilde M,\tilde g,J) such that, for any nonzero vector X \in T_pM, p \in M, the angle \theta(X) between JX and the tangent space T_pM is independent of the choice of p\in M and X \in T_pM. The first results on slant submanifolds were summarized in the book [7]. Since then slant submanifolds have been studied by many geometers. Many nice results on slant submanifolds have been obtained …
A Homotopy For A Complex Of Free Lie Algebras, Michele Vergne
A Homotopy For A Complex Of Free Lie Algebras, Michele Vergne
Turkish Journal of Mathematics
Using the Guichardet construction, we compute the cohomology groups of a complex of free Lie algebras introduced by Alekseev and Torossian
Best Simultaneous Approximation In Function And Operator Spaces, Eyad Abu-Sirhan
Best Simultaneous Approximation In Function And Operator Spaces, Eyad Abu-Sirhan
Turkish Journal of Mathematics
Let Z be a Banach space and G be a closed subspace of Z. For f_1,f_2 \in Z, the distance from f_1,f_2 to G is defined by d(f_1,f_2,G) = \underset{f \in G}{\inf} max { f_1-f , f_2-f }. An element g^{\ast} \in G satisfying max { f_1-g^{\ast } , f_2-g^{\ast } } = \underset{f \in G}{\inf } max { f_1-f , f_2-f } is called a best simultaneous approximation for f_1,f_2 from G. In this paper, we study the problem of best simultananeous approximation in the space of all continuous X-valued functions on a compact Hausdorff space S; C(S,X), and …
On The Order Of Weighted Approximation By Positive Linear Operators, Tüli̇n Coşkun
On The Order Of Weighted Approximation By Positive Linear Operators, Tüli̇n Coşkun
Turkish Journal of Mathematics
An estimation of approximation of continuous functions by positive linear operators in weighted norm using the weighted modulus of continuity is established. Application of the main result to the known Gadjiyev-Ibragimov operators is given.
C^*-Convexity And C^*-Faces In *-Rings, Ali Ebrahimi Meymand, Gholam Hossein Esslamzadeh
C^*-Convexity And C^*-Faces In *-Rings, Ali Ebrahimi Meymand, Gholam Hossein Esslamzadeh
Turkish Journal of Mathematics
Existence of rich algebraic, geometric and topological structures on self-adjoint operator algebras raises the general question that, for a particular theorem which of these structures have made the result work. The present paper is an effort toward the answer of this question, by investigating the role of algebraic structure in the subject of C^*-convexity. In this paper, we extend the notions of C^*-convexity, C^*-extreme point and C^*-face to *-rings and we study some of their properties. We introduce the notion of C^*-convex map on C^*-convex subsets of a *-ring. Moreover we identify optimal points of some unital *-homomorphisms on some …
Invariant Parametrizations And Complete Systems Of Global Invariants Of Curves In The Pseudo-Euclidean Geometry, Ömer Pekşen, Djavvat Khadjiev, İdri̇s Ören
Invariant Parametrizations And Complete Systems Of Global Invariants Of Curves In The Pseudo-Euclidean Geometry, Ömer Pekşen, Djavvat Khadjiev, İdri̇s Ören
Turkish Journal of Mathematics
Let M(n, p) be the group of all transformations of an n-dimensional pseudo-Euclidean space E^n_p of index p generated by all pseudo-orthogonal transformations and parallel translations of E^n_p. Definitions of a pseudo-Euclidean type of a curve, an invariant parametrization of a curve and an M(n, p)-equivalence of curves are introduced. All possible invariant parametrizations of a curve with a fixed pseudo-Euclidean type are described. The problem of the M(n, p)-equivalence of curves is reduced to that of paths. Global conditions of the M(n, p)-equivalence of curves are given in terms of the pseudo-Euclidean type of a curve and the system …
Oscillation Of Third-Order Nonlinear Delay Difference Equations, Mustafa Fahri̇ Aktaş, Aydin Ti̇ryaki̇, Ağacik Zafer
Oscillation Of Third-Order Nonlinear Delay Difference Equations, Mustafa Fahri̇ Aktaş, Aydin Ti̇ryaki̇, Ağacik Zafer
Turkish Journal of Mathematics
Third-order nonlinear difference equations of the form \Delta (c_n\Delta (d_n\Delta x_n))+p_n\Delta x_{n+1}+q_nf(x_{n-\sigma})=0, n\geq n_{0} are considered. Here, {c_n}, {d_n}, {p_n}, and {q_n} are sequences of positive real numbers for n_0 \in N, f is a continuous function such that f(u) /u\geq K > 0 for u \neq 0. By means of a Riccati transformation technique we obtain some new oscillation criteria. Examples are given to illustrate the importance of the results.
Generalized Berwald Metrics, Esmaeil Peyghan, Akbar Tayebi
Generalized Berwald Metrics, Esmaeil Peyghan, Akbar Tayebi
Turkish Journal of Mathematics
In this paper, we consider a class of Finsler metrics called generalized Berwald metrics which contains the class of Berwald metrics as a special case. We prove that every generalized Berwald metrics with non-zero scalar flag curvature or isotropic Berwald curvature is a Randers metric. Then we prove that on generalized Berwald metrics, the notions of generalized Landsberg and Landsberg curvatures are equivalent.
Banach Limit And Some New Spaces Of Double Sequences, Mohammad Mursaleen, Syed Abdul Mohiuddine
Banach Limit And Some New Spaces Of Double Sequences, Mohammad Mursaleen, Syed Abdul Mohiuddine
Turkish Journal of Mathematics
In this paper, we define and study the Banach limit for double sequences and introduce some new spaces related to the concept of almost and strong almost convergence for double sequences. We characterize these spaces through some sublinear functionals and we also establish some inclusion relations.
On Normality Of Meromorphic Functions With Multiple Zeros And Sharing Values, Youming Wang
On Normality Of Meromorphic Functions With Multiple Zeros And Sharing Values, Youming Wang
Turkish Journal of Mathematics
In this paper we study the problem of normal families of meromorphic functions concerning shared values. Let F be a family of meromorphic functions in the plane domain D \subseteq C and n be a positive integer. Let a, b be two finite complex constants such that a \neq 0. If n \geq 3 and f + a(f')^n and g + a(g')^n share b in D for every pair of functions f, g \in F, then F is normal in D. And some examples are provided to show the result is sharp.
Invariant Subspaces Of Weakly Compact-Friendly Operators, Mert Çağlar, Remzi̇ Tunç Misirlioğlu
Invariant Subspaces Of Weakly Compact-Friendly Operators, Mert Çağlar, Remzi̇ Tunç Misirlioğlu
Turkish Journal of Mathematics
We prove that if a non-zero weakly compact-friendly operator B on a Banach lattice with topologically full center is locally quasi-nilpotent, then the super right-commutant [B\rangle of B has a non-trivial closed invariant ideal. An example of a weakly compact-friendly operator which is not compact-friendly is also provided.
Results Of Generalized Local Cohomology Modules Of A-Minimax Modules, Hero Saremi
Results Of Generalized Local Cohomology Modules Of A-Minimax Modules, Hero Saremi
Turkish Journal of Mathematics
Let R be a commutative Noetherian ring, M a finitely generated R-module, and N a minimax R-module. It is shown that if a is an ideal of R, such that cd(a)=1, where cd is the cohomological dimension of a in R, then H_a^j(M, N) and Ext_R^i(M,H_a^j(N)) are a-cominimax for all i,j. Furthermore, if t is a non-negative integer such that H_a^j(M, N) is a-minimax for all j
P-Rank And P-Groups In Algebraic Groups, Adrien Deloro
P-Rank And P-Groups In Algebraic Groups, Adrien Deloro
Turkish Journal of Mathematics
A few remarks on the measures of the p-rank of a group equipped with a dimension, including the refutation of a result of Burdges and Cherlin.
Secrecy Logic: S-Secrecy Structures, George Voutsadakis
Secrecy Logic: S-Secrecy Structures, George Voutsadakis
Turkish Journal of Mathematics
Let S = \lan L,\vdash_S\ran be a deductive system. An S-secrecy logic is a quadruple K = \lan Fm_L(V),K,B,S\ran, where Fm_L(V) is the algebra of L-formulas, K,B are S-theories, with B \subseteq K and S \subseteq K such that S \cap B = \emptyset. K corresponds to information deducible from a knowledge base, B to information deducible from the publicly accessible (or browsable) part of the knowledge base and S is a secret set, a set of sensitive or private information that the knowledge base aims at concealing from its users. To provide models for this context, the notion of …
Product Of Graded Submodules, Ameer Jaber
Product Of Graded Submodules, Ameer Jaber
Turkish Journal of Mathematics
Let \Delta be an abelian group. By considering the notion multiplication of \Delta-graded modules (see [7]) over a commutative \Delta-graded ring with unity, we introduce the notion of product of two \Delta-graded submodules which we use to characterize the \Delta-graded prime submodules of a multiplication \Delta-graded module. Finally we proved a graded version of Nakayama lemma for multiplication \Delta-graded modules.
The Character Variety Of A Class Of Rational Links, Khaled Qazaqzeh
The Character Variety Of A Class Of Rational Links, Khaled Qazaqzeh
Turkish Journal of Mathematics
Let G_n be the fundamental group of the exterior of the rational link C(2n) in Conway's normal form, see [7]. A presentation for G_n is given by \langle a, b (ab)^n = (ba)^n\rangle [3, Thm. 2.2]. We study the character variety in SL(2, C) of the group G_n. In particular, we give the defining polynomial of the character variety of G_n. As an application, we show a well-known result that G_n and G_m are isomorphic only when n = m. Also as a consequence of the main theorem of this paper, we give a basis of the Kauffman bracket skein …
Weakly Normal Rings, Junchao Wei̇, Libin Li
Weakly Normal Rings, Junchao Wei̇, Libin Li
Turkish Journal of Mathematics
A ring R is defined to be weakly normal if for all a, r \in R and e \in E(R), ae = 0 implies Rera is a nil left ideal of R, where E(R) stands for the set of all idempotent elements of R. It is proved that R is weakly normal if and only if Rer(1-e) is a nil left ideal of R for each e \in E(R) and r \in R if and only if T_n(R, R) is weakly normal for any positive integer n. And it follows that for a weakly normal ring R (1) R is …
On F_S-Supplemented Primary Subgroups Of Finite Groups, Lujin Zhu, Long Miao
On F_S-Supplemented Primary Subgroups Of Finite Groups, Lujin Zhu, Long Miao
Turkish Journal of Mathematics
Let G be a finite group and F a formation of finite groups. A subgroup H of G is called F_s-supplemented in G if there exists a subnormal subgroup T of G such that G = HT and (H \cap T)H_G/H_G is contained in the F-hypercenter Z^F_{\infty}(G/H_G) of G/H_G. In this paper, we study the structure of finite groups by using F_s-supplemented subgroups.
On Cosets In Coxeter Groups, Sarah B. Hart, Peter J. Rowley
On Cosets In Coxeter Groups, Sarah B. Hart, Peter J. Rowley
Turkish Journal of Mathematics
In this paper the notion of Coxeter length for a subset of a Coxeter group, as introduced in [9], is investigated for various subsets of a Coxeter group. Mostly cosets of various subgroups are examined as well as the associated idea of X-posets, which is a vast generalization of the Bruhat order.
Small Covers Over Products Of A Polygon With A Simplex, Yanying Wang, Yanchang Chen
Small Covers Over Products Of A Polygon With A Simplex, Yanying Wang, Yanchang Chen
Turkish Journal of Mathematics
The equivariant homeomorphism class of an (orientable) small cover over a simple convex polytope P^n bijectively corresponds to the equivalence class of its (orientable) coloring under the action of automorphism group of face poset of P^n. By calculating the number of orbits of group actions we determine the number of equivariant homeomorphism classes of small covers over products of a polygon with a simplex. Moreover, we calculate the number of equivariant homeomorphism classes of all orientable small covers over the product.
On \Alpha-Skew Mccoy Modules, Jian Cui, Jianlong Chen
On \Alpha-Skew Mccoy Modules, Jian Cui, Jianlong Chen
Turkish Journal of Mathematics
Let \alpha be a ring endomorphism. Extending the notions of McCoy modules and \alpha-skew McCoy rings, we introduce the notion of \alpha-skew McCoy modules, which can also be regarded as a generalization of \alpha-skew Armendariz modules. A number of illustrative examples are given. Various properties of these modules are developed, and equivalent conditions for \alpha-skew McCoy modules are established. Furthermore, we study the relationship between a module and its polynomial module.