http://jims-a.org/index.php/jimsa/issue/feedJournal of the Indonesian Mathematical Society2023-12-08T21:31:41+00:00Editorialjims.indoms@gmail.comOpen Journal Systems<div><strong>Journal title</strong> : Journal of The Indonesian Mathematical Society</div> <div><strong>Initials</strong> : JIMS</div> <div><strong>Abbreviation</strong> : J. Indones. Math. Soc.</div> <div><strong>Frequency</strong> : 3 issues per year (March, July, and November)</div> <div><strong>DOI prefix</strong> : <a href="https://search.crossref.org/?q=2086-8952">10.22342</a> by<img src="https://jims-a.org/public/site/images/admin/crossref-logo-stacked-rgb-small-a41f52ed695a710d6a57355cc9ee7d7c.png" alt="" width="52" height="14" /></div> <div><strong>ISSN</strong> : <a href="http://u.lipi.go.id/1274193789">2086-8952</a> (p) | <a href="http://u.lipi.go.id/1432110804">2460-0245</a> (e)</div> <div><strong>Editor-in-chief</strong> : <a href="https://www.scopus.com/authid/detail.uri?authorId=16053675900">Indah Emilia Wijayanti</a></div> <div><strong>Executive Editor</strong> : <a href="https://www.scopus.com/authid/detail.uri?authorId=24480624100">Fajar Adi Kusumo</a></div> <div><strong>Managing Editor</strong> : <a href="https://www.scopus.com/authid/detail.uri?authorId=57050754900">Hazrul Iswadi</a></div> <div><strong>Journal Rank </strong>: <strong><a href="https://www.scopus.com/sourceid/21101064980" target="_blank" rel="noopener">CiteScore</a> - Q4 (<em>General Mathematics</em>) </strong>&<strong><a href="https://mjl.clarivate.com/search-results?issn=2086-8952&hide_exact_match_fl=true&utm_source=mjl&utm_medium=share-by-link&utm_campaign=journal-profile-share-this-journal" target="_blank" rel="noopener"> JCI</a> - Q4 (<em>Mathematics</em>)</strong></div> <div><strong>Publishing Model </strong>: Open Access, <a href="http://jims-a.org/index.php/jimsa/apc">Author(s) Pay</a></div> <div><strong>Publisher</strong> : <a href="https://indoms.id/en/home/">The Indonesian Mathematical Society</a></div>http://jims-a.org/index.php/jimsa/article/view/1594Topological Indices of Relative g-noncommuting Graph of Dihedral Groups2023-12-07T07:14:53+00:00Nur Ain Supunurainsupu23@gmail.comIntan Muchtadi-Alamsyahntan@itb.ac.idErma Suwastikaermasuwastika@itb.ac.id<p>Let G be a finite group, H be a subgroup of G and g be a fixed element of G. The relative g-noncommuting graph Γ(g,H,G) of G is defined as a graph with vertex set is G and two distinct vertices x and y are adjacent if [x, y] ̸= g or [x, y] ̸= g−1, where at least x or y belong to H. In this paper, we will discuss the relative g-non-commuting graph of the dihedral groups D(2n), in particular case when n is an odd number. We give several topological indices of the relative g-noncommuting graph of the dihedral groups D2n including the first Zagreb index, Wiener index, Edge-Wiener index, Hyper-Wiener index, and Harary index.</p>2023-11-30T00:00:00+00:00Copyright (c) 2023 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1596Revisiting Kantorovich Operators in Lebesgue Spaces2023-12-07T14:03:01+00:00Maximillian Ventura Obiemaxvobie@gmail.comErick Angga Taebenuetaebenu@gmail.comReinhart Gunadireinhart.gunadi@gmail.comDenny Ivanal Hakimdhakim@itb.ac.id<p>According to the Weierstrass Approximation Theorem, any continuous function on the closed and bounded interval can be approximated by polynomials. A constructive proof of this theorem uses the so-called Bernstein polynomials. For the approximation of integrable functions, we may consider Kantorovich operators as certain modifications for Bernstein polynomials. In this paper, we investigate the behaviour of Kantorovich operators in Lebesgue spaces. We first give an alternative proof of the uniform boundedness of Kantorovich operators in Lebesgue spaces by using the Riesz-Thorin Interpolation Theorem. In addition, we examine the convergence of Kantorovich operators in the space of essentially bounded functions. We also give an example related to the rate of convergence of Kantorovich operators in a subspace of Lebesgue spaces.</p>2023-11-30T00:00:00+00:00Copyright (c) 2023 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1597Effects of Inversion Layer on The Atmospheric Pollutant Dispersion from A High Chimney2023-12-07T21:24:58+00:00Fidelis Nofertinus Zaifidelisnofertinus@gmail.comAgus Yodi Gunawanayodi@itb.ac.id<pre>An inversion layer is a layer in the lower atmosphere at a certain height through which there is no transport of pollutants. It plays as a significant factor in the formation of air pollutants where they are trapped. In this paper, a mathematical model describing an atmospheric pollutant dispersion from a high chimney in the presence of an inversion layer is constructed. The aim of the model is to predict the concentration of pollutants at ground level. The advection-diffusion equation governs the concentration of a pollutant released into the air. An analytical solution procedure via the integral transforms is presented for the steady-state case. Solutions are entirely determined by two parameters, i.e., the source strength emanating from the chimney and the height of the inversion layer. The pollutant concentration on the ground level with some multiple source formations will be explored, and also for various values of inversion layer height. Results show that the lower the inversion layer, the higher the pollutant concentration on the ground level is.</pre>2023-11-30T00:00:00+00:00Copyright (c) 2023 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1598On The Adjoint of Bounded Operators On A Semi-Inner Product Space2023-12-08T14:12:42+00:00R. Respitawulanyuliawan@office.itb.ac.idQori Y. Pangestuyuliawan@office.itb.ac.idElvira Kusniyantiyuliawan@office.itb.ac.idFajar Yuliawanyuliawan@office.itb.ac.idPudji Astutiyuliawan@office.itb.ac.id<pre>The notion of semi-inner product (SIP) spaces is a generalization of inner product (IP) spaces notion by reducing the positive definite property of the product to positive semi-definite. As in IP spaces, the existence of an adjoint of a linear operator on a SIP space is guaranteed when the operator is bounded. However, in contrast, a bounded linear operator on SIP space can have more than one adjoint linear operators. In this article we give an alternative proof of those results using the generalized Riesz Representation Theorem in SIP space. Further, the description of all adjoint operators of a bounded linear operator in SIP space is identified.</pre>2023-11-30T00:00:00+00:00Copyright (c) 2023 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1599A note on some Endpoint Estimates of Commutators of Fractional Integral Operators2023-12-08T21:31:41+00:00Verrel Rievaldo Wijayaarywijaya86@gmail.comDenny Ivanal Hakimdhakim@itb.ac.idMarcus Wono Setya Budhiwono@math.itb.ac.id<pre>It is known that fractional integral operators are not bounded from Lebesgue integrable functions to Lebesgue space for some particular related exponent. Based on some recent results by Schikorra, Spector, and Van Schaftingen, we investigate commutators of fractional integral operators on Lebesgue integrable functions. We establish a weak type estimates for these commutators generated by essentially bounded functions. Under the same assumption, we also prove that the norm of these commutators are dominated by the norm of the Riesz transform.</pre>2023-11-30T00:00:00+00:00Copyright (c) 2023 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1262Homomorphisms of Complex Kumjian-Pask Algebras2023-06-25T13:54:01+00:00Rizky Rosjanuardirizky@upi.eduEndang Cahya Mulyaning Asihendangcahya@gmail.comAl Azhary Mastaalazhari.masta@upi.edu<p>Let Λ and Γ be row finite k-graphs without sources. We show that ∗-algebra homomorphisms ϕ : KPC(Λ) → KPC(Γ) extend to ∗-algebra homomorphisms ϕ¯ : C∗(Λ) → C∗(Γ). We also examine necessary and sufficient conditions for algebra homomorphisms between complex Kumjian-Pask algebras KPC(Λ) and KPC(Γ) which are ∗-preserving.</p>2023-11-30T00:00:00+00:00Copyright (c) 2024 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1190Minimum Roman Dominating Distance Energy of A Graph2023-06-09T11:40:42+00:00Lakshmanan Rlakshmsc2004@yahoo.co.inAnnamalai Nalgebra.annamalai@gmail.com<p>In this correspondence, we introduced the concept of minimum roman dominating distance energy ERDd(G) of a graph G and computed minimum roman dominating distance energy of some standard graphs. Also, we discussed the properties of eigenvalues of a minimum roman dominating distance matrix ARDd(G). Finally, we derived the upper and lower bounds for ERDd(G).</p>2023-12-31T00:00:00+00:00Copyright (c) 2024 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1337A Unified Distance Approach for Ranking Fuzzy Numbers and Its Comparative Reviews2023-09-14T03:24:09+00:00Shiv Prasad Prasadshpd1512@gmail.comShatabdi Sinhashatabdi778@gmail.com<p>Even though a large number of research studies have been presented in recent years for ranking and comparing fuzzy numbers, the majority of existing techniques suffer from plenty of shortcomings. These shortcomings include counterintuitiveness, the inability to distinguish the fuzzy number and its partnered image, and the inconsistent ability to distinguish symmetric fuzzy numbers and fuzzy numbers that represent the compensation of areas. To overcome the cited drawbacks, this paper suggests a unified distance that multiplies the centroid value (weighted mean value) of the fuzzy number on the horizontal axis and a linear sum of the<br />distances of the centroid points of the left and right fuzziness areas from the original<br />point through an indicator. The indicator reflects the attitude of the left and<br />right fuzziness of the fuzzy number, we can call it the indicator of fuzziness. To use<br />this technique, the membership functions of the fuzzy numbers need not be linear.<br />That is the proposed approach can also rank the fuzzy numbers with non-linear<br />membership functions. The suggested technique is highly convenient and reliable to<br />discriminate the symmetric fuzzy numbers and the fuzzy numbers having compensation<br />of areas. The advantages of the proposed approach are illustrated through<br />examples that are common for a wide range of numerical studies and comparisons<br />with several representative approaches, that existed in the literature.</p>2023-11-30T00:00:00+00:00Copyright (c) 2024 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1412A New Notion of Inner Product in A Subspace of n-Normed Spaces2023-11-28T07:35:54+00:00Muh Nurmuhammadnur@unhas.ac.idMochammad Idrismoch.idris@ulm.ac.id<p>Given an n-normed space X for n>= 2$, we investigate the completness of Y (as subspace of X) respect to a new norm that corresponds this new inner product on Y. Moreover, we discuss the angle between two subspaces in Y.</p>2023-11-30T00:00:00+00:00Copyright (c) 2024 Journal of the Indonesian Mathematical Societyhttp://jims-a.org/index.php/jimsa/article/view/1451Forecasting Dependent Tail Value-at-Risk by ARMA-GJR-GARCH-Copula Method and Its Application in Energy Risk2023-08-14T08:00:17+00:00Bony Parulian Josaphatbonyp@stis.ac.id<p>One widely known risk measure is Tail Value-at-Risk (TVaR), which is<br />the average of the values of random risk that exceed the Value-at-Risk (VaR). This<br />classic risk measure of TVaR does not take into account the excess of another random<br />risk (associated risk) that may have an effect on target risk. Copula function expresses a methodology that represents the dependence structure of random variables<br />and has been used to create a risk measure of Dependent Tail Value-at-Risk (DTVaR). Incorporating copula into the forecast function of the ARMA-GJR-GARCH<br />model, this article argues a novel approach, called ARMA-GJR-GARCH-copula<br />with Monte Carlo method, to calculate the DTVaR of dependent energy risks. This<br />work shows an implementation of the ARMA-GJR-GARCH-copula model in forecasting the DTVaR of energy risks of NYH Gasoline and Heating oil associated with<br />energy risk of WTI Crude oil. The empirical results demonstrate that, the simpler<br />GARCH-Clayton copula is better in forecasting DTVaR of Gasoline energy risk than<br />the MA-GJR-GARCH-Clayton copula. On the other hand, the more complicated<br />MA-GJR-GARCH-Frank copula is better in forecasting DTVaR of Heating oil energy risk than the GARCH-Frank copula. In this context, energy sector market<br />players should invest in Heating oil because the DTVaR forecast of Heating oil is<br />more accurate than that of Gasoline.</p>2023-11-30T00:00:00+00:00Copyright (c) 2024 Journal of the Indonesian Mathematical Society