https://www.ajol.info/index.php/qm/issue/feedQuaestiones Mathematicae2024-06-20T15:28:57+00:00Publishing Managerpublishing@nisc.co.zaOpen Journal Systems<p><em>Quaestiones Mathematicae</em> is devoted to research articles from a wide range of mathematical areas. Longer expository papers of exceptional quality are also considered. Published in English, the journal receives contributions from authors around the globe and serves as an important reference source for anyone interested in mathematics.</p> <p>Read more about the journal <a href="http://www.nisc.co.za/products/12/journals/quaestiones-mathematicae" target="_blank" rel="noopener">here</a>. </p>https://www.ajol.info/index.php/qm/article/view/272287Inverse problem of determining the coefficient in a sixth order Boussinesq equation with additional nonlocal integral condition2024-06-20T12:58:04+00:00A.S. Farajova.farajov@mail.ruM.J. Huntula.farajov@mail.ruYashar T. Mehraliyeva.farajov@mail.ru<p>The work is devoted to the study of the solvability of the inverse boundary value problem with an unknown time depended coefficient for a sixth-order Boussinesq equation with an additional integral condition of the first kind is investigated. First, the given problem is reduced to an equivalent problem in a certain sense. Then, using the Fourier method the equivalent problem is reduced to solving the system of integral equations. The existence and uniqueness of a solution to the system of integral equation is proved by the contraction mapping principle. This solution is also the unique solution to the equivalent problem. Finally, by equivalence, the theorem of existence and uniqueness of a classical solution to the given problem is proved. The sixth order Boussinesq-Type problem is discretized using the Quintic B-spline (QB-spline) collocation technique and reshaped as non-linear least-squares optimization of the Tikhonov regularization function. This is numerically solved by means of the MATLAB subroutine lsqnonlin tool. Both perturbed data and analytical solution are inverted. Numerical outcomes are reported and discussed. In addition, the von Neumann stability analysis for the proposed numerical approach has also been discussed. </p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272290Spectrum of the Cesaro-Hardy operator in rearrangement invariant spaces2024-06-20T13:25:22+00:00Meiram Akhymbekakhymbek@math.kzKanat Tulenovakhymbek@math.kzGulnur Zaurakhymbek@math.kz<p>No Abstract</p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272292Remote sublocales2024-06-20T13:30:36+00:00Mbekezeli Nxumalo69969949@mylife.unisa.ac.za<p>We use the notion of a remote collection of a Tychonoff space to define a remote sublocale of any locale. Our definition is conservative, in the sense that, a subset is remote if and only if the sublocale it induces is remote in the locale of opens. We characterize remote sublocales and show that the Booleanization of a locale is the largest remote sublocale of the locale, a result with no pointset topological counterpart. We study localic maps that send remote sublocales back and forth. It turns out that the localic maps which preserve remote sublocales are precisely those with skeletal left adjoints.</p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272293Generalized derivations with nilpotent values in semiprime rings2024-06-20T13:35:38+00:00Cheng-Kai Liuckliu@cc.ncue.edu.tw<p>No Abstract</p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272295Orbit spaces of free involutions on the product of three spheres2024-06-20T13:47:07+00:00Dimpidimpipaul2@gmail.comHemant Kumar Singhdimpipaul2@gmail.com<p>In this paper, we have determined the orbit spaces of free involutions on a finitistic space having mod 2 cohomology of the product of three spheres S<sup>n</sup> ×S<sup>m</sup> ×S<sup>l</sup>, 1 ≤ n ≤ <em>m</em> ≤ <em>l</em>. This paper generalizes the results proved by Dotzel et al. [7] for free involutions on the product of two sphere S<sup>n</sup> ×S<sup>m</sup>, 1 ≤ n ≤ m. As an application, we have also derived the Borsuk-Ulam type results.</p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272296Planar polynomial of the graphs2024-06-20T14:03:17+00:00Behnaz Tolueb.tolue@gmail.comAlireza Doostabadi b.tolue@gmail.com Sayed Masih Ayat b.tolue@gmail.com <p>In this paper, the planar polynomial of a graph is introduced and some of its properties are discussed. The planar polynomial of the graph G is real-rooted if and only if G is planar. This polynomial is not EE-invariant. Some useful results about the roots of planar polynomial of complete graphs are presented. Moreover, all the graphs whose planar polynomial is of degree five are characterized.</p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272297On the way to Frolicher bornology2024-06-20T14:15:35+00:00Ben Moditi Mahuduben.mahudu@wits.ac.zaMukinayi Hermenegilde Tshilomboben.mahudu@wits.ac.za<p>In this work we introduce the concept of bornology on the theory of Fr¨olicher spaces. A canonical bornology, called the functional bornology, is induced from structure functions, and bounded maps under this bornology are determined. Based on the structure of structure curves, we deduce that we cannot induce, canonically, a bornology from structure curves. For each of Fr¨olicher subspace and product, an initial and functional bornology are induced and compared. Similarly, for each of Fr¨olicher quotient and coproduct, a final and functional bornology are induced and compared.</p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272298Exponential decay of solutions to an inertial model for a wave equation with viscoelastic damping and time varying delay2024-06-20T14:51:47+00:00Mohamed Berbicheberbichemed@yahoo.fr<p>In the present work, we study the global existence and uniform decay rates of solutions to the initial-boundary value problem related to the dynamic behavior of evolution equations accounting for rotational inertial forces along with a linear time-nonlocal Kelvin-Voigt damping arising in viscoelastic materials. By constructing appropriate Lyapunov functional, we show that the solution converges to the equilibrium state exponentially in the energy space.</p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272299On a-normaloid d-tuples of operators and related questions2024-06-20T14:58:03+00:00Najla Altwaijrynajla@ksu.edu.saSilvestru Sever Dragomirnajla@ksu.edu.saKais Fekinajla@ksu.edu.sa<p>No Abstract</p>2024-06-20T00:00:00+00:00Copyright (c) 2024 https://www.ajol.info/index.php/qm/article/view/272300Lattice characterization of extreme positive operators2024-06-20T15:02:22+00:00Jamel Jaberjamel.jaber@free.frAdnen Khalfaouijamel.jaber@free.fr<p>We present a lattice-based characterization of extreme points whithin well-defined convex subsets of positive operators, operating between Banach lattices with quasi-interior points.</p>2024-06-20T00:00:00+00:00Copyright (c) 2024