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Vol.30 No.2

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Abstract

In this paper, we introduce a second order linear differential operator <sup>T</sup>&#x25A1;: C<sup>&#x221E;</sup> (M) &#x2192; C<sup>&#x221E;</sup> (M) as a natural generalization of Cheng-Yau operator, [8], where T is a (1, 1)-tensor on Riemannian manifold (M, h), and then we show on compact Riemannian manifolds, divT = divT<sup>t</sup>, and if divT = 0, and f be a smooth function on M, the condition <sup>T</sup>&#x25A1; f = 0 implies that f is constant. Hereafter, we introduce T-energy functionals and by deriving variations of these functionals, we define T-harmonic maps between Riemannian manifolds, which is a generalization of L<sub>k</sub>-harmonic maps introduced in [3]. Also we have studied fT-harmonic maps for conformal immersions and as application of it, we consider fL<sub>k</sub>-harmonic hypersurfaces in space forms, and after that we classify complete fL<sub>1</sub>-harmonic surfaces, some fL<sub>k</sub>-harmonic isoparametric hypersurfaces, fL<sub>k</sub>-harmonic weakly convex hypersurfaces, and we show that there exists no compact fL<sub>k</sub>-harmonic hypersurface either in the Euclidean space or in the hyperbolic space or in the Euclidean hemisphere. As well, some properties and examples of these definitions are given.

B. R. Srivatsa Kumar ; Dongkyu Lim ; Arjun K. Rathie pp.131-138 https://doi.org/https://doi.org/10.7468/jksmeb.2023.30.2.131
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Abstract

The aim of this note is to provide two new and interesting closed-form evaluations of the generalized hypergeometric function <sub>5</sub>F<sub>4</sub> with argument <TEX>$\frac{1}{256}$</TEX>. This is achieved by means of separating a generalized hypergeometric function into even and odd components together with the use of two known sums (one each) involving reciprocals of binomial coefficients obtained earlier by Trif and Sprugnoli. In the end, the results are written in terms of two interesting combinatorial identities.

Tanmay Biswas ; Chinmay Biswas pp.139-154 https://doi.org/https://doi.org/10.7468/jksmeb.2023.30.2.139
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In this paper we wish to prove some results relating to the growth rates of composite entire and meromorphic functions with their corresponding left and right factors on the basis of their generalized relative order (&#x03B1;, &#x03B2;) and generalized relative lower order (&#x03B1;, &#x03B2;), where &#x03B1; and &#x03B2; are continuous non-negative functions defined on (-&#x221E;, +&#x221E;).

Ae Young Ko ; Jae Gil Choi pp.155-167 https://doi.org/https://doi.org/10.7468/jksmeb.2023.30.2.155
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Abstract

In this paper, we use a vector-valued conditioning function to define a conditional Fourier-Feynman transform (CFFT) and a conditional convolution product (CCP) on the Wiener space. We establish the existences of the CFFT and the CCP for bounded functionals which form a Banach algebra. We then provide fundamental relationships between the CFFTs and the CCPs.

Mohamed Rossafi ; Abdelkarim Kari pp.169-190 https://doi.org/https://doi.org/10.7468/jksmeb.2023.30.2.169
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In this paper, we introduce an extension of rectangular metric spaces called controlled rectangular metric spaces, by changing the rectangular inequality in the definition of a metric space. We also establish some fixed point theorems for self-mappings defined on such spaces. Our main results extends and improves many results existing in the literature. Moreover, an illustrative example is presented to support the obtained results.

Nesir Huseyin ; Anar Huseyin pp.191-201 https://doi.org/https://doi.org/10.7468/jksmeb.2023.30.2.191
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In this paper the control system described by Urysohn type integral equation is studied. It is assumed that control functions are integrally constrained. The trajectory of the system is defined as multivariable continuous function which satisfies the system's equation everywhere. It is shown that the set of trajectories is Lipschitz continuous with respect to the parameter which characterizes the bound of the control resource. An upper estimation for the diameter of the set of trajectories is obtained. The robustness of the trajectories with respect to the fast consumption of the remaining control resource is discussed. It is proved that every trajectory can be approximated by the trajectory obtained by full consumption of the control resource.

Reza Memarbashi ; Milad Tahavor pp.203-220 https://doi.org/https://doi.org/10.7468/jksmeb.2023.30.2.203
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Abstract

A new modification of the SIS epidemic model incorporating the adaptive host behavior is proposed. Unlike the common situation in most epidemic models, this system has two disease-free equilibrium points, and we were able to prove that as the basic reproduction number approaches the threshold of 1, these two points merge and a Bogdanov-Takens bifurcation of codimension three occurs. The occurrence of this bifurcation is a sign of the complexity of the dynamics of the system near the value 1 of basic reproduction number. Both local and global stability of disease-free and endemic equilibrium point are studied.

Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics