Communications of the
Korean Mathematical Society
CKMS

ISSN(Print) 1225-1763 ISSN(Online) 2234-3024

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  • 2022-07-31

    A robust numerical technique for solving non-linear Volterra integro-differential equations with boundary layer

    Firat Cakir, Musa Cakir, Hayriye Guckir~Cakir

    Abstract : In this paper, we study a first-order non-linear singularly perturbed Volterra integro-differential equation (SPVIDE). We discretize the problem by a uniform difference scheme on a Bakhvalov-Shishkin mesh. The scheme is constructed by the method of integral identities with exponential basis functions and integral terms are handled with interpolating quadrature rules with remainder terms. An effective quasi-linearization technique is employed for the algorithm. We establish the error estimates and demonstrate that the scheme on Bakhvalov-Shishkin mesh is $O(N^{-1})$ uniformly convergent, where $N$ is the mesh parameter. The numerical results on a couple of examples are also provided to confirm the theoretical analysis.

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  • 2022-07-31

    Multi-derivations and some approximations

    Abasalt Bodaghi, Hassan Feizabadi

    Abstract : In this paper, we introduce the multi-derivations on rings and present some examples of such derivations. Then, we unify the system of functional equations defining a multi-derivation to a single formula. Applying a fixed point theorem, we will establish the generalized Hyers--Ulam stability of multi-derivations in Banach module whose upper bounds are controlled by a general function. Moreover, we give some important applications of this result to obtain the known stability outcomes.

  • 2022-07-31

    A characterization of finite factorization positive monoids

    Harold Polo

    Abstract : We provide a characterization of the emph{positive monoids} (i.e., additive submonoids of the nonnegative real numbers) that satisfy the finite factorization property. As a result, we establish that positive monoids with well-ordered generating sets satisfy the finite factorization property, while positive monoids with co-well-ordered generating sets satisfy this property if and only if they satisfy the bounded factorization property.

  • 2023-04-30

    $C_{12}$-space forms

    Gherici Beldjilali, Nour Oubbiche

    Abstract : The aim of this paper is two-fold. First, we study the Chinea-Gonzalez class $C_{12}$ of almost contact metric manifolds and we discuss some fundamental properties. We show there is a one-to-one correspondence between $C_{12}$ and K\"ahlerian structures. Secondly, we give some basic results for Riemannian curvature tensor of $C_{12}$-manifolds and then establish equivalent relations among $\varphi$-sectional curvature. Concrete examples are given.

  • 2023-04-30

    Generalized Varignon's and medial triangle theorems

    Francesco Laudano

    Abstract : In this paper, we extend the medial triangle theorem and Varignon's theorem to generic two-dimensional polygons and highlight the role played by diagonals in this process. One of the results is a synthetic definition of the concept of median for an $n$-sided polygon.

  • 2022-07-31

    A translation of an analogue of Wiener space with its applications on their product spaces

    Dong Hyun Cho

    Abstract : Let $C[0,T]$ denote an analogue of Weiner space, the space of real-valued continuous on $[0,T]$. In this paper, we investigate the translation of time interval $[0,T]$ defining the analogue of Winer space $C[0,T]$. As applications of the result, we derive various relationships between the analogue of Wiener space and its product spaces. Finally, we express the analogue of Wiener measures on $C[0,T]$ as the analogue of Wiener measures on $C[0,s]$ and $C[s,T]$ with $0

  • 2024-04-30

    Geometric properties of starlikeness involving hyperbolic cosine function

    Om P. Ahuja, Asena Çetinkaya, Sushil Kumar

    Abstract : In this paper, we investigate some geometric properties of starlikeness connected with the hyperbolic cosine functions defined in the open unit disk. In particular, for the class of such starlike hyperbolic cosine functions, we determine the lower bounds of partial sums, Briot-Bouquet differential subordination associated with Bernardi integral operator, and bounds on some third Hankel determinants containing initial coefficients.

  • 2023-01-31

    Some results involving the representation of the centralizer of a matrix

    Smail Bouarga

    Abstract : In this paper, we investigate the dimension and the structure of the centralizer of a square matrix with entries from an arbitrary field.

  • 2022-07-31

    New volume comparison with almost Ricci soliton

    Shahroud azami, Sakineh Hajiaghasi

    Abstract : In this paper we consider a condition on the Ricci curvature involving vector fields which enabled us to achieve new results for volume comparison and Laplacian comparison. These results in special case obtained with considering volume non-collapsing condition. Also, by applying this condition we get new results of volume comparison for almost Ricci solitons.

  • 2023-01-31

    Detectable means and applications

    Mustapha Ra\"{\i}ssouli

    Abstract : In this paper, we introduce a new concept for bivariate means and we study its properties. Application of this concept for mean-inequal\-ities is also discussed. Open problems are derived as well.

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April, 2024
Vol.39 No.2

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