Physical Sciences and Mathematics Commons^™

An Investigation Of New Associated Curves Of A Frenet Curve In Euclidean N-Space, Bedi̇a Meri̇h Özçeti̇n

Turkish Journal of Mathematics

In this study, we introduce the V2-direction curve, Vn−1-direction curve and Vn-direction curve of a Frenet curve in n-dimensional Euclidean space. We provide characterizations and investigate the relationships between the Frenet apparatus of the principal curve and the corresponding apparatus of the direction curves. We also present an application for all direction curves with the results shown using computer code implemented in MATLAB.

New Structures Of Golden Type On The Tangent Bundle, Simona-Luiza Druta-Romaniuc, Cristina-Elena Hretcanu, Aydin Gezer

Turkish Journal of Mathematics

The aim of our paper is to prove the existence of some types of almost (α, p)–golden structures, obtained as general natural lifts of the Riemannian metric from the base manifold M to the total space TM of the tangent bundle. We show that TM, endowed with a general natural almost (α, p)–golden structure (which is a generalisation of the golden structure) and with a general natural metric, is an almost (α, p)–golden Riemannian manifold if and only if the function coefficients of the almost (α, p)–golden structure are related to …

Corrigendum To “ Improved Berezin Radius Inequalities For Functional Hilbert Space Operators” [Turkish Journal Of Mathematics 49 (5) 2025 545-561], Mojtaba Bakherad, Ulaş Yamanci, Mohammad W. Alomari

Turkish Journal of Mathematics

In the article entitled Improved Berezin radius inequalities for functional Hilbert space operators, published in the Turkish Journal of Mathematics, [49 (5): 545-561. https://doi.org/10.55730/1300-0098.3607], the affiliation of the author MOHAMMAD W. ALOMARI was published incorrectly due to an error at the submission stage. The incorrect affiliation was Department of Mathematics, Faculty of Science and Information Technology, Irbid National University, Irbid, Jordan T he correct affiliation is Department of Mathematics, Faculty of Science, Jadara University, Irbid, Jordan T he authors apologize for any inconvenience caused.

The original article can be accessed at: https://doi.org/10.55730/1300-0098.3607

Monotone Positive Solutions Of Impulsive Differential Equations Asymptotic To Nonprincipal Solutions, Si̇bel Doğru Akgöl, Ağacik Zafer

Turkish Journal of Mathematics

This study investigates the asymptotic behavior of monotone positive solutions for a general class of nonlinear second-order impulsive differential equations. By employing the principal and nonprincipal solutions of the associated homogeneous equation, we establish the existence of a monotone positive solution asymptotic to a nonprincipal solution at infinity. To achieve this, we also prove a compactness criterion for an effective use of Schauder’s fixed-point theorem. Under suitable conditions, similarly to the classical case, it is demonstrated that a monotone positive solution asymptotic to a nonprincipal solution exists. A concrete example is given to illustrate the results.

Improved Berezin Radius Inequalities For Functional Hilbert Space Operators, Mojtaba Bakherad, Ulaş Yamanci, Mohammad W. Alomari

Turkish Journal of Mathematics

The Berezin number of an operator S is defined by ber(S) = sup_λ∈Θ |Ŝ(λ)| = sup_λ∈Θ |⟨Sĸ̂_λ, ĸ̂_λ⟩|, where Ŝ(λ) = ⟨Sĸ̂_λ, ĸ̂_λ⟩ (λ ∈ Θ) is the Berezin transform of an operator S on the functional Hilbert space ℋ = ℋ(Θ) and ĸ̂_λ = ĸ_λ / ‖ĸ_λ‖ is the normalized reproducing kernel of ℋ. In this paper, we show an improvement of the classical Cauchy–Schwarz inequality involving the Berezin number. Moreover, some Berezin numbers inequalities are proven for invertible operators.

Application On Convolution For Fuzzy Differential Subordination Of Meromorphic Functions, Kholood Mohamed Alsager, Fethi̇ye Müge Sakar, Alina Alb Lupas, Sheza Mohamed El-Deeb

Turkish Journal of Mathematics

This paper investigates fuzzy differential subordinations involving meromorphic functions defined in the punctured unit disk. A novel operator based on the Hadamard product (also known as convolution) is introduced to establish new results in the theory of fuzzy differential subordination. This operator provides a generalized framework that extends classical analytic methods to the fuzzy setting, offering new insights into the geometric behavior of meromorphic functions under fuzzy conditions. Several sufficient conditions for fuzzy differential subordination are derived, and their connections to existing results are discussed. The findings contribute to the growing body of literature at the intersection of classical geometric …

(Α, Β)-Normal Differential Operators For First Order In Hilbert Spaces Of Vector-Functions, Zameddin I. Ismailov, Pembe İpek Al

Turkish Journal of Mathematics

In this article, the relationships between (α, β)-normality properties of the extensions of the minimal operator generated by the first-order differential operator expression in the Hilbert spaces of vector-functions in a finite interval and the variable operator coefficients of this differential operator expression are investigated. Then, the general form of all (α, β)-normal extensions of the minimal operator in these spaces is determined under the constraints obtained for the coefficient operators.

Applications Of A New Linear Operator Involving Dziok-Srivastava Operator And Bessel Function Of The First Kind, Daniela Andrada Bardac-Vlada, Georgia Irina Oros

Turkish Journal of Mathematics

This study introduces a new linear operator constructed from the well-known Dziok–Srivastava linear hypergeometric operator, the Bessel function of the first kind, and convolution. Applying the new operator, a class of functions with positive real part is defined and investigated concerning inclusion relations, the necessary and sufficient conditions for functions to belong to this class, as well as starlikeness and convexity conditions. The properties of the new class to be convex of a certain order, close-to-convex and starlike of a certain order are highlighted and examples are also included to prove that the new outcome is applicable. The methods employed …

On Certain Subclasses Of Starlike And Convex Functions With Respect To T-Symmetric Points, Osman Altintaş, Ni̇zami̇ Mustafa

Turkish Journal of Mathematics

In this study, we defined for the first time a new subclass of stalike and convex functions in the open unit disk of the complex plane and we examined coefficiend upper bound estimates for this class.

On Multiplicative Order Convergence And Multiplicative Order Continuous Operators, Hüma Gürkök, Bahri̇ Turan

Turkish Journal of Mathematics

Let A and B be two f-algebras. This paper establishes the theoretical framework for multiplicative order convergence, clarifying its definition, properties, and relations to other convergence types. This includes a detailed discussion on the conditions under which multiplicative order convergence and order convergence, as well as unbounded order convergence, mutually imply each other. We establish an extension theorem for multiplicative order continuous operators, similar to Veksler’s theorem for order continuous operators. As a result of this theorem, we derive the order structure of the space of multiplicative order continuous operators. We show that the space L_mo(A, …

Majorization Properties For Analytic Functions With Positive Real Part, Oya Mert

Turkish Journal of Mathematics

The majorization feature is important when investigating analytical functions’ geometric properties. The present work focuses on the majorization property for a general Ma-Minda type function class S^*_φ(γ, λ) of starlike functions of complex order, which is described with the Ruscheweyh differential operator. In the context of the main theorem, consequences are presented for various special functions φ having a positive real part. Furthermore, the Ruscheweyh differential operator extends a representation formula and investigates an upper-bound formula. Examples of upper bounds for analytic functions are also presented.

Nonoscillatory Solutions Of Third-Order Nonlinear Dynamic Equations: Existence And Nonexistence, Özkan Öztürk, Elvan Akin, Nesli̇han Nesli̇ye Pelen

Turkish Journal of Mathematics

This paper investigates a third-order nonlinear dynamic equation on arbitrary time scales, a nonempty closed subset of the real numbers, unifying continuous and discrete analyses. We study the qualitative behavior of nonoscillatory solutions and their quasi-derivatives, focusing on their limiting behaviors. The existence of such solutions are established using improper integral criteria and Schauder’s and Knaster’s fixed point theorems. In addition, we establish the criteria for the nonexistence of nonoscillatory solutions. Furthermore, we prove the existence of Kneser-type solutions of the corresponding linear dynamic equation on isolated time scales, addressing an open problem in the literature. Several examples of theoretical …

Structural Stability For Damped Nonlinear Wave Equations, Sevda Isayeva, Varga Kalantarov

Turkish Journal of Mathematics

We study the problem of continuous dependence on parameters for solutions to initial-boundary value problems for nonlinear strongly damped wave equations. Specifically, we consider three classes of equations: a strongly damped wave equation with a nonlinear damping term; a strongly damped wave equation incorporating both a nonlinear damping term and a nonlinear source term; and a strongly damped wave equation with a nonlinear source term and a linear weak damping term. For each class, we establish structural stability results, showing that the solutions depend continuously on the relevant parameters.

The Action Of The Superposition Operator On Weighted Banach Sequence Spaces LP,Σ, Nermin Okičić, Fehim Dedagić

Turkish Journal of Mathematics

We consider a nonlinear superposition operator on weighted Banach spaces l_p,σ, where σ is the weighted function with the property that (∀n ∈ ℕ) σ(n) ≥ 1. We present the necessary and sufficient conditions for the action of the superposition operator from l_p,σ to l_q,τ, 1 ≤ p, q ≤ ∞, as well as the L-characteristic of the action of the considered operator.

The Geometry Of Semislant Submersions Whose Total Manifolds Are Locally Conformal Kähler Manifolds, Çağrihan Çi̇men, Hakan Mete Taştan

Turkish Journal of Mathematics

We study semislant submersions whose total manifolds are locally conformal Kähler manifolds. We provide conditions for the total geodesicity and integrability of the distributions involved in the definition. Next, we establish a condition under which such a submersion is a Clairaut submersion. Finally, we obtain some optimal inequalities for a semislant submersion whose total manifold is Hopf space form.

The Generalization Of Rectifying Helices, Bülent Altunkaya

Turkish Journal of Mathematics

This work establishes connections between different classes of arbitrary speed rectifying helices. We further analyze how the involute of a space curve can exhibit spherical helicity and how the evolute can inherit rectifying properties, thereby providing an alternative characterization of these helices. These relationships, along with their interplay with involutes and evolutes, are supported by illustrative examples that offer deeper insights into their geometric properties.

Some Properties Of Rescaled Sasaki Type Metric On The Coframe Bundle, Habil Fattayev, Arif Salimov

Turkish Journal of Mathematics

In this paper we introduce the rescaled Sasaki type metric on the coframe bundle of a Riemannian manifold and investigate the Levi-Civita connection, curvature tensor, paracomplex structures of coframe bundle with this metric

Janowski Close-To-Convexity Harmonic Mappings, Bushra Arif, Jacek Dziok, Wasim Ul Haq, Mohsan Raza

Turkish Journal of Mathematics

In the present work we introduce harmonic univalent functions related to Janowski close-to-convexity and we provide their necessary and sufficient criteria. The extreme points and topological features of such harmonic mappings will also be investigated. By applying extreme points theory, we obtain integral mean inequalities, distortion theorems, and coefficient estimates for families of harmonic functions.

Approximate Controllability Of Fractional Backward Stochastic Differential Inclusions With Order 1/2 < P < 1, Müberaa Selah

Turkish Journal of Mathematics

In this paper, fractional backward stochastic differential equations are extended to multivalued forms. Since the problem of approximate controllability of the obtained fractional backward stochastic differential inclusions has not yet been addressed in the literature, we focus on the approximate controllability of these systems. The study’s main results, such as existence of the mild solution and approximate controllability for fractional backward stochastic differential inclusions, have been proven through fractional calculus, Bohnenblust-Karlin Theorem, and appropriate conditions.

The Circular Sum Of Points Of An Affine Segment, Mircea Crasmareanu, Marius Munteanu

Turkish Journal of Mathematics

This note introduces a sum for two interior points of an affine segment [AB] based on a trigonometric approach. Some properties of this operation, along with general examples (including squares of endpoints, the midpoint, and the centroid), are discussed. A main result is that the midpoint of a segment is the circular sum of the points dividing the segment with the ratios 4 and 9. In addition, we completely solve a Diophantine equation associated with the circular sum in order to identify all points with integer ratio whose circular sum is a point with integer ratio.

Weighted Inequalities For Discrete Bilinear Hardy-Type Operator With A Matrix, Nazerke Zhangabergenova, Ainur Temirkhanova

Turkish Journal of Mathematics

In this paper, we consider a new discrete bilinear inequality of Hardy-type involving a matrix operator. We establish weight characterizations of this inequality under some conditions on the matrix entries.

New Characterizations Of Weights In Dynamic Inequalities Of Hardy's Type On Time Scales, Mario Krnic, Mahmoud M. Osman, Samir H. Saker

Turkish Journal of Mathematics

The main aim of this paper is to establish some new characterizations of the weights in Hardy-type dynamic inequality, dual Hardy-type inequality, andreverse Hardy-type dynamic inequality on time scales. Some integral and discrete inequalities due to Copson, Leindler, and Hyun and Kim will bededuced as special cases. Moreover, new dynamic inequalities via convexity are proved.

Analytical Solution And Stability Of Ψ-Prabhakar Delayed Systems: Application To Antibiotic Production, Mustafa Aydin

Turkish Journal of Mathematics

The analytical solution of the linear ψ -Prabhakar delay differential equations is explored using the method of variation of parameters, in which a ψ -general delayed exponential matrix function is introduced. The ψ -Prabhakar calculus is enhanced in terms of the semi-group property, inversion results, and several simplified calculations and relations. The system's stability is analyzed within the framework of Ulam-Hyers stability. Finally, the theoretical findings are validated through an application to antibiotic production.

Integral Extensions On Growth And Higher Derivatives Of A Polynomial, Nirmal Kumar Singha, Fahreddi̇n G. Abdullayev, Barchad Chanam

Turkish Journal of Mathematics

A well-known theorem due to Ankeny and Rivlin states that if p(z) is a polynomial of degree n such that p(z) has no zero in |z| < 1, then
max_|z|=R≥1 |p(z)| ≤ (R^{n + 1} / 2) max_|z|=1 |p(z)|.
This research examines the polynomial p(z), ensuring that it has no zero in the disk |z| < k, where k ≥ 1. At the same time, we investigate the s^th derivative of this polynomial, where 0 ≤ s < n. In our effort to establish integral formulations of the inequalities related to the derivatives of this class of polynomials, we have successfully extended and generalized Ankeny and Rivlin’s inequality to integral settings. Additionally, part of our findings provides integral analogs of results by Mir [J. Anal., 27 (2019), 851−857]. Moreover, another aspect of our work leads to an improvement in the result of Jain [Turk. J. Math., 31 (2007), 89−94], which we have also verified using an example. We have also compared our results with a previously known result using this numerical example, where the bounds that are in terms of integral means are estimated numerically by numerical integration using Simpson’s 1/3^rd rule and illustrate graphically the obtained inequalities as regards sharpness.

On The Solutions Of Difference Equations Of The Volterra Type, Hakan Adigüzel

Turkish Journal of Mathematics

In this paper, we conduct a thorough analysis of the qualitative behavior of solutions to three different types of difference equations of the Volterra type. Utilizing the principles of discrete calculus and various well-known inequalities, we have presented our findings. To conclude our theoretical findings, we provide several examples that illustrate full alignment with the findings.

The Concept Of T-Basis And Vector-Valued Hardy Classes, Bilal Bilalov, Sabina Rahib Sadigova

Turkish Journal of Mathematics

This paper introduces the concept of a t-basis generated by some bilinear mapping t(·;·). It is considered the vector-valued class L_p(X) := L_p(J; X), 1 ≤ p < +∞, where J = [−π, π] and X is a Banach space with the UMD property, and it is proven that the classical system of exponents {e^int}_n∈ℤ forms a t-basis for L_p(X), 1 < p < +∞. Using this fact, the Hardy vector classes _nH_p^±(X), 1 < p < +∞, different from the classical ones, are defined, and an equivalent definition of these classes is given and some of their properties are studied. In addition, the concept of t-Riesz property of a system of exponentials is introduced in L_p(X), 1 < p < +∞, and it is proved that this system has the t-Riesz property. A new method is given for establishing the Plemelj–Sokhotski formulas for X-valued Cauchy type integrals when X has the UMD property. An abstract analogue of the “1/4-Kadets” theorem is obtained for …

Continuous Dependence Of Thermoelasticity Problem, Müge Meyvaci, Şevket Gür

Turkish Journal of Mathematics

The current study considers the initial boundary value problem for the thermoelastic model. The model in which heat conduction is given by Green and Naghdi's theory is called Type II. It is increasingly accepted that studying the structural stability of the initial boundary value problem is crucial. This is because even minor changes in the equation or its coefficients can lead to significant variations in the solution of the problem. From this point of view, we analyze the structural stability of the solutions, specifically examining the continuous dependence of the solutions on all the coefficients of the thermoelastic system, using …

Order Structure Of Order-To-Topological Continuous Operator, Gül Si̇nem Keleş, Bahri̇ Turan, Bi̇rol Altin

Turkish Journal of Mathematics

Let J be a vector lattice, and W be a topological vector space. An operator K: J → W is called an order-to-topological continuous operator if u_α → 0 in J implies K(u_α) → 0 in W for each net (u_α) in J. In this study, we examine the order structure of the space of order-to-topological continuous operators in general and the order structure of order-to-norm continuous operators in particular. We study the relationships between order-to-topology continuous operators and other classes of operators, such as order weakly compact and order continuous operators. Moreover, we give …

Fractional Equivalent Of Fourth-Order Laguerre And Chebyshev Polynomials, Zahra Kavousi, Kazem Ghanbari

Turkish Journal of Mathematics

Orthogonal polynomials have very useful properties in the solution of mathematical and physical problems. In the last few years, there has been considerable interest in the properties of orthogonal polynomials satisfying differential equations (DE) of order greater than two, their connection to singular boundary value problems, their generalizations, and their classification as solutions of second-order DE. In this paper, we develop a fractional analog of the fourth-order Laguerre differential equation on the interval [0, ∞) and, in addition, we develop a fractional analog of the fourth-order Chebyshev differential equation on a symmetric interval [−α, α], where α is the order …

A Note On A Novel Type Of Alster Covering Property In Bitopological Setting, Necati̇ Can Açikgöz, Ceren Sultan Elmali

Turkish Journal of Mathematics

In this paper, we introduce a new type of Alster covering property in bitopological setting. We investigate its relations with other existing covering properties. By giving counterexamples, we indicate that our new property is different than other mentioned properties. We also construct some conditions for equivalences of those properties with the corresponding property. We also consider the preservation of this new form of bitopological Alster covering property. We investigate the productivity of bitopological nearly Lindelöfness and bitopological nearly Mengerness.