{"title":"Bilinear θ-type Calderón–Zygmund operators and its commutator on generalized weighted Morrey spaces over RD-spaces","authors":"Suixin He , Shuangping Tao","doi":"10.1016/j.rinam.2025.100587","DOIUrl":"10.1016/j.rinam.2025.100587","url":null,"abstract":"<div><div>An RD-space <span><math><mi>X</mi></math></span> is a space of homogeneous type in the sense of Coifman and Weiss with the extra property that a reverse doubling property holds in <span><math><mi>X</mi></math></span>. The authors establish the boundedness of the bilinear <span><math><mi>θ</mi></math></span>-type Calderón–Zygmund operator <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>θ</mi></mrow></msub></math></span> and its commutator <span><math><mrow><mo>[</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>θ</mi></mrow></msub><mo>]</mo></mrow></math></span> in this setting. These are generated by the function <span><math><mrow><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>∈</mo><mi>B</mi><mi>M</mi><mi>O</mi><mrow><mo>(</mo><mi>μ</mi><mo>)</mo></mrow></mrow></math></span> and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>θ</mi></mrow></msub></math></span> on generalized weighted Morrey space <span><math><mrow><msup><mrow><mi>M</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>ϕ</mi></mrow></msup><mrow><mo>(</mo><mi>ω</mi><mo>)</mo></mrow></mrow></math></span> and generalized weighted weak Morrey space <span><math><mrow><mi>W</mi><msup><mrow><mi>M</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>ϕ</mi></mrow></msup><mrow><mo>(</mo><mi>ω</mi><mo>)</mo></mrow></mrow></math></span> over RD-spaces.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100587"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144116024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Chromatic number of random graphs: An approach using a recurrence relation","authors":"Yayoi Abe, Auna Setoh, Gen Yoneda","doi":"10.1016/j.rinam.2025.100600","DOIUrl":"10.1016/j.rinam.2025.100600","url":null,"abstract":"<div><div>The vertex coloring problem to find chromatic numbers is known to be unsolvable in polynomial time. Although various algorithms have been proposed to efficiently compute chromatic numbers, they tend to take an enormous amount of time for large graphs. In this paper, we propose a recurrence relation to rapidly obtain the expected value of the chromatic number of random graphs. Then we compare the results obtained using this recurrence relation with other methods using an exact investigation of all graphs, the Monte Carlo method, the iterated random color matching method, and the method presented in Bollobás’ previous studies.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100600"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144253792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical solution and errors analysis of iterative method for a nonlinear plate bending problem","authors":"Akakpo Amoussou Wilfried , Houédanou Koffi Wilfrid","doi":"10.1016/j.rinam.2025.100576","DOIUrl":"10.1016/j.rinam.2025.100576","url":null,"abstract":"<div><div>This paper uses the HCT finite element method and mesh adaptation technology to solve the nonlinear plate bending problem and conducts error analysis on the iterative method, including a priori and a posteriori error estimates. Our investigation exploits Hermite finite elements such as BELL and HSIEH-CLOUGH-TOCHER (HCT) triangles for conforming finite element discretization. We use an iterative resolution algorithm to linearize the associated discrete problem and study the convergence of this algorithm towards the solution of the approximate problem. An optimal a priori error estimation has been established. We construct a posteriori error indicators by distinguishing between discretization and linearization errors and prove their reliability and optimality. A numerical test is carried out and the results obtained confirm those established theoretically.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100576"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A new numerical approach for solving space–time fractional Schrödinger differential equations via fractional-order Chelyshkov functions","authors":"Somayeh Nemati , Salameh Sedaghat , Sajedeh Arefi","doi":"10.1016/j.rinam.2025.100584","DOIUrl":"10.1016/j.rinam.2025.100584","url":null,"abstract":"<div><div>In this paper, a numerical method for solving space–time fractional Schrödinger equations is proposed. The method employs fractional-order Chelyshkov functions and their properties to derive the remainders associated with the main problem. The Riemann–Liouville fractional integral operator is applied to the basis functions, yielding exact results through the analytical representation of Chelyshkov polynomials. The real and imaginary parts of the functions involved in the problem are separated, transforming the Schrödinger equation into two equations. By approximating the fractional derivative of the unknown function and using a set of collocation points, the problem is reduced to a system of algebraic equations, the solution of which provides the numerical solution to the problem. Additionally, an error analysis is presented. Finally, numerical examples and their results demonstrate the efficiency and accuracy of the proposed scheme.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100584"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144071845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Conformal prediction across scales: Finite-sample coverage with hierarchical efficiency","authors":"Ali Baheri , Marzieh Amiri Shahbazi","doi":"10.1016/j.rinam.2025.100589","DOIUrl":"10.1016/j.rinam.2025.100589","url":null,"abstract":"<div><div>We propose a multi-scale extension of conformal prediction, an approach that constructs prediction sets with finite-sample coverage guarantees under minimal statistical assumptions. Classic conformal prediction relies on a single notion of “conformity” overlooking the multi-level structures that arise in applications such as image analysis, hierarchical data exploration, and multi-resolution time series modeling. In contrast, the proposed framework defines a distinct conformity function at each relevant scale or resolution, producing multiple conformal predictors whose prediction sets are then intersected to form the final multi-scale output. We establish theoretical results confirming that the multi-scale prediction set retains the marginal coverage guarantees of the original conformal framework and can, in fact, yield smaller or more precise sets in practice. By distributing the total miscoverage probability across scales in proportion to their informative power, the method further refines the set sizes. We also show that the dependence between scales can lead to conservative coverage, ensuring that the actual coverage exceeds the nominal level. Numerical experiments in a synthetic classification setting demonstrate that multi-scale conformal prediction achieves or surpasses the nominal coverage level while generating smaller prediction sets compared to single-scale conformal methods.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100589"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144166906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Capacity constraints in ball and urn distribution problems","authors":"Jingwei Li, Thomas G. Robertazzi","doi":"10.1016/j.rinam.2025.100592","DOIUrl":"10.1016/j.rinam.2025.100592","url":null,"abstract":"<div><div>This paper explores the distribution of indistinguishable balls into distinct urns with varying capacity constraints, a foundational issue in combinatorial mathematics with applications across various disciplines. We present a comprehensive theoretical framework that addresses both upper and lower capacity constraints under different distribution conditions, elaborating on the combinatorial implications of such variations. Through rigorous analysis, we derive analytical solutions that cater to different constrained environments, providing a robust theoretical basis for future empirical and theoretical investigations. These solutions are pivotal for advancing research in fields that rely on precise distribution strategies, such as physics and parallel processing. The paper not only generalizes classical distribution problems but also introduces novel methodologies for tackling capacity variations, thereby broadening the utility and applicability of distribution theory in practical and theoretical contexts.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100592"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144231525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fractional Routh-Hurwitz conditions and nonlinear dynamics in some 3D and 4D dynamical systems modeled by Caputo-Fabrizio operators","authors":"A.E. Matouk","doi":"10.1016/j.rinam.2025.100588","DOIUrl":"10.1016/j.rinam.2025.100588","url":null,"abstract":"<div><div>This work presents stability conditions in some 2D, 3D and 4D dynamical systems modeled by Caputo-Fabrizio operators. Some theorems about fractional Routh-Hurwitz criteria are presented and proven in two-, three-, four- and n-dimensional dynamical systems governed by the Caputo-Fabrizio derivatives. The stability analyzes are presented for all equilibrium states of four examples representing two 3D and two 4D chaotic systems governed by the Caputo-Fabrizio derivatives. The conditions of Hopf bifurcations in these systems are also discussed in the considered chaotic systems. In addition, the chaotic dynamics in these systems are illustrated via numerical simulations that show existences of periodic orbits and several types of chaotic dynamics, such as one-scroll chaos, double scroll-chaos, self-excited chaos, and an alien face chaotic attractor. The Lyapunov exponents and bifurcation diagrams are successfully utilized to measure these chaotic and hyperchaotic states.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100588"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144069305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Multivariate spatial conditional U-quantiles: a Bahadur–Kiefer representation","authors":"Salim Bouzebda, Nourelhouda Taachouche","doi":"10.1016/j.rinam.2025.100593","DOIUrl":"10.1016/j.rinam.2025.100593","url":null,"abstract":"<div><div>Quantiles constitute a core concept in probability theory and theoretical statistics, providing an indispensable instrument in a wide array of applications. Although the univariate notion of quantiles is intuitively clear and mathematically well established, extending this concept to a multivariate framework poses significant theoretical and practical challenges. A well-established approach to extending univariate quantiles to the multivariate setting is the <em>spatial</em> (or <em>geometric</em>) framework, whose empirical counterparts exhibit notable robustness and admit an elegant Bahadur–Kiefer representation. Independently, another generalization of univariate quantiles leads to <span><math><mi>U</mi></math></span><em>-quantiles</em>, which naturally encompass classical estimators such as the Hodges–Lehmann estimator for a central tendency. In this study, we bridge these perspectives by introducing <em>multivariate conditional spatial</em> <span><math><mi>U</mi></math></span><em>-quantiles</em> and deriving their corresponding Bahadur–Kiefer representation. This representation enables us to establish fundamental theoretical properties, including weak convergence and a law of the iterated logarithm. These results are proved under some standard structural conditions on the Vapnik–Chervonenkis classes of functions and some mild conditions on the model. The uniform limit theorems discussed in this paper are key tools for further developments in data analysis involving empirical process techniques.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100593"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144185197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Functional dimensionality of Koopman eigenfunction space","authors":"Ido Cohen , Eli Appleboim , Gershon Wolansky","doi":"10.1016/j.rinam.2025.100585","DOIUrl":"10.1016/j.rinam.2025.100585","url":null,"abstract":"<div><div>This work presents the general form solution of <em>Koopman Partial Differential Equation</em> for an autonomous system of <span><math><mi>N</mi></math></span> ordinary differential equations. We identify a domain in <span><math><msup><mrow><mi>R</mi></mrow><mrow><mi>N</mi></mrow></msup></math></span> for which any number in the complex plane is an eigenvalue of the Koopman operator, and all eigensolutions are obtained from <span><math><mrow><mi>N</mi><mo>−</mo><mn>1</mn></mrow></math></span> functionally independent invariants of the system. Thus, we demonstrate that one may, in principle, diagonalize the system with only <span><math><mi>N</mi></math></span> functionally independent Koopman eigenfunctions.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100585"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144189426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analysis and numerical solution of some minimal time control problems","authors":"Enrique Fernández-Cara , Irene Marín Gayte","doi":"10.1016/j.rinam.2025.100582","DOIUrl":"10.1016/j.rinam.2025.100582","url":null,"abstract":"<div><div>This paper is devoted to the theoretical and numerical analysis of some minimal time control problems associated to linear and nonlinear differential equations. We start by studying simple cases concerning linear and nonlinear ODEs. Then, we deal with the heat equation. In all these situations, we analyze the existence of solutions, we deduce optimality results and we present several algorithms for the computation of optimal controls. Finally, we illustrate the results with several numerical experiments.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"26 ","pages":"Article 100582"},"PeriodicalIF":1.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144107206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}