{"title":"Resolving implicit nonconvex state-dependent sweeping processes in Banach spaces","authors":"Bushra R. Al-Sinan","doi":"10.1016/j.rinam.2026.100756","DOIUrl":"10.1016/j.rinam.2026.100756","url":null,"abstract":"<div><div>We study a nonconvex implicit sweeping process in which the moving constraint set depends on both time and the state variable. The analysis is carried out in a 2-uniformly convex and smooth Banach space via a generalized projection approach based on a duality mapping. By transforming the differential inclusion into an explicit evolution equation and imposing a suitable growth condition, we establish the existence of Lipschitz solutions. Several examples are provided to illustrate the applicability of the main results.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"31 ","pages":"Article 100756"},"PeriodicalIF":1.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148776288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A potential exploring of a multi-dimensional coupled Burgers–Fisher–Huxley equation using finite volume and element methods (FVM/FEM)","authors":"Tarik Chakkour","doi":"10.1016/j.rinam.2026.100753","DOIUrl":"10.1016/j.rinam.2026.100753","url":null,"abstract":"<div><div>The purpose of this work is to examine an intensive investigation of the framework based on Finite Element (FE) and Finite Volume (FV) methods to solve the generalized Burgers–Fisher–Huxley (BFH) equation. These methods are explored here to approximate these solutions in higher dimensional space, highlighting some of their properties on the existence and uniqueness of bounded and positive solutions. Convergent numerical schemes are presented. Particularly, the second-order FV scheme is achieved by implementing a predictor–corrector method. In which slightly different forms of the limiter solvers are applied to resolve the left–right degeneracy on the interface by solving the Riemann problem. The purpose of using a limiter is to reduce the slope near the extrema, which is shown on FV grid with the original data. An FE scheme capable of preserving this property, which is directly related to the continuous Galerkin (CG) and indirectly to discontinuous Galerkin (DG), is proposed. Highly accurate solutions are obtained by the framework that shows its flexibility in solving different problems. The convergence behavior is observed between all the methods by controlling viscosity to demonstrate a striking agreement between the numerical and analytical solutions.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"31 ","pages":"Article 100753"},"PeriodicalIF":1.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148776289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On Gabor frame networks","authors":"Jamkhongam Touthang","doi":"10.1016/j.rinam.2026.100746","DOIUrl":"10.1016/j.rinam.2026.100746","url":null,"abstract":"<div><div>This paper studies Gabor frame networks whose hidden units are time–frequency shifts of a fixed window and whose trainable parameters are synthesis coefficients. Finite Gabor subnetworks are shown to approximate every element of the closed frame span, with an explicit truncation estimate in terms of canonical dual coefficients. For sampled learning, the paper derives least-squares, ridge-regularized, and Wirtinger-gradient training rules under suitable window regularity. Stability, density-based architectural constraints, and extensions to tensor-product, adaptive, multiscale, and multilayer architectures are also discussed. A numerical experiment is included to illustrate sampled coefficient training and prediction accuracy for finite Gabor frame networks.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"31 ","pages":"Article 100746"},"PeriodicalIF":1.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148737421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
José Augusto Fontenele Magalhães, Muhammad Fuady Emzir, Francesco Corona
{"title":"Pathwise approximations to solving the filtering problem for the stochastic chemostat","authors":"José Augusto Fontenele Magalhães, Muhammad Fuady Emzir, Francesco Corona","doi":"10.1016/j.rinam.2026.100757","DOIUrl":"10.1016/j.rinam.2026.100757","url":null,"abstract":"<div><div>This paper concerns the inverse problem of characterising the state of a bioreactor from observations. In laboratory settings, the bioreactor is represented by a device called a chemostat. We consider a differential description of the evolution of the state of the chemostat under environmental fluctuations. We model the state evolution as a stochastic process driven by Brownian motion. Under this model, the state is described by its probability distribution in time, given the distribution of the initial state. The corresponding probability density function solves a deterministic partial differential equation (PDE), the Kolmogorov forward equation. This description is refined by incorporating observations. More formally, we seek the conditional distribution of the state given an observation process as the solution to a filtering problem, with the corresponding conditional probability density function solving a non-linear stochastic PDE, the Kushner–Stratonovich equation. In numerical studies of bioreactors, the well-posedness of these differential equations is frequently assumed rather than verified. Consequently, it remains unclear whether unique solutions exist and whether numerical approximations preserve key qualitative properties, such as positivity (e.g. non-negative chemical concentrations). This paper establishes the existence and uniqueness of solutions, ensuring well-posedness before presenting numerical approximations. Furthermore, we approximate the pathwise solution to the filtering problem by three approaches: a PDE-based approximation combining finite difference and splitting methods, a classical sequential Monte Carlo method, and a linearisation method. Our results show that the first two provide a richer probabilistic description of the state than the linearisation method, making them suitable for bioreactor control architectures.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"31 ","pages":"Article 100757"},"PeriodicalIF":1.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148934371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A higher-order L1-2-3 tension spline scheme for nonlinear two-dimensional time-fractional reaction–diffusion equation","authors":"Alemu Senbeta Bekela, Lemi Guta Enyadene, Mesfin Mekuria Woldaregay, Zerihun Kinfe Birhanu","doi":"10.1016/j.rinam.2026.100749","DOIUrl":"10.1016/j.rinam.2026.100749","url":null,"abstract":"<div><div>The paper presents the design and analysis of a high-order numerical scheme for nonlinear two-dimensional time-fractional reaction–diffusion equations. The Caputo time-fractional derivative is approximated using the L1-2-3 scheme, while the spatial derivatives are discretized by means of tension spline difference scheme. The existence, uniqueness, and regularity of the solution are established to support the theoretical analysis. The truncation error, stability, and convergence of the proposed method are rigorously investigated. Two test problems are considered to validate the accuracy and efficiency of the method. For sufficiently smooth solutions, the proposed method is shown to be unconditionally stable and to achieve fourth-order spatial accuracy and <span><math><mrow><mo>(</mo><mn>4</mn><mo>−</mo><mi>α</mi><mo>)</mo></mrow></math></span>-order temporal accuracy. The numerical results confirm the theoretical convergence rates and demonstrates that the proposed method provides higher accuracy, improved convergence behavior, and competitive computational efficiency compared with existing numerical methods. These results indicate that the proposed method is an effective and reliable approach for solving nonlinear two-dimensional time-fractional reaction–diffusion equations with sufficiently smooth solutions arising in models with memory and hereditary effects.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"31 ","pages":"Article 100749"},"PeriodicalIF":1.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148776383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A novel RKHS method for solving space–time FDEs","authors":"Sizhe Wang, Yibo Yang, Wenyan Wang","doi":"10.1016/j.rinam.2026.100708","DOIUrl":"10.1016/j.rinam.2026.100708","url":null,"abstract":"<div><div>A high-performance reproducing kernel Hilbert spaces (RKHS) numerical framework is formulated for space–time fractional differential equations (FDEs). Advanced optimization strategies reduce computational complexity from non-local fractional operators, overcoming limitations of traditional reproducing kernel (RK) methods. Dispensing with the complex Gram–Schmidt Orthogonalization (GSO), the framework is easy to implement. Theoretical analyses confirm asymptotic convergence of approximate solutions, and comparative tests validate its superiority in generating high-precision global approximate solutions for space–time FDEs with error accumulation issues.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"30 ","pages":"Article 100708"},"PeriodicalIF":1.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147951754","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":"Stability of purely convective steady-states of fractional Boussinesq equations in an exterior domain","authors":"Zhi-Min Chen","doi":"10.1016/j.rinam.2026.100712","DOIUrl":"10.1016/j.rinam.2026.100712","url":null,"abstract":"<div><div>A thermal convection flow in the three-dimensional unbounded fluid domain exterior to a sphere is considered. The viscosity force is determined by a fractional power of the Stokes operator. A purely conductive steady state arises due to the fluid heated from the sphere. A weak solution of the fluid motion problem is obtained and global stability of the steady-state solution in <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> is provided.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"30 ","pages":"Article 100712"},"PeriodicalIF":1.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147951753","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":"Accelerated iterative simultaneous hard thresholding algorithm for joint sparse optimization","authors":"Heran Huang , Zihe Zheng , Xinlin Hu , Yifan Ye","doi":"10.1016/j.rinam.2026.100711","DOIUrl":"10.1016/j.rinam.2026.100711","url":null,"abstract":"<div><div>Joint sparse optimization (JSO) leverages the shared sparsity structure across multiple measurement vectors to enhance the signal recovery capability in various applications. In this paper, we propose an accelerated iterative simultaneous hard thresholding algorithm with gradient-based momentum for the JSO, and establish its approximate global convergence under the simultaneous restricted isometry property. Numerical experiments on simulated data demonstrate that the proposed algorithm converges faster and exhibits superior stability compared to several existing simultaneous algorithms.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"30 ","pages":"Article 100711"},"PeriodicalIF":1.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147995253","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":"Corrigendum to “Analytical strength-duration curve for the spiking response of the LIF neuron to an alpha-function-shaped excitatory current pulse” [Results Appl. Math. 25 (2025) 100548]","authors":"Alexander Paraskevov","doi":"10.1016/j.rinam.2026.100713","DOIUrl":"10.1016/j.rinam.2026.100713","url":null,"abstract":"","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"30 ","pages":"Article 100713"},"PeriodicalIF":1.5,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148523005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fungi as functors: A category-theoretic approach to mycelial organisation","authors":"Andrew Adamatzky","doi":"10.1016/j.rinam.2026.100715","DOIUrl":"10.1016/j.rinam.2026.100715","url":null,"abstract":"<div><div>We develop a category-theoretic foundation for fungal organisation. A fungal organism is formalised as a functor from a category <span><math><mi>Env</mi></math></span> of structured environmental states and admissible transformations to a category <span><math><mi>Myc</mi></math></span> of mycelial network states and biologically meaningful morphisms. An operational program category <span><math><mi>Prog</mi></math></span> models time-ordered exposure protocols, and a semantics functor <span><math><mrow><msub><mrow><mi>F</mi></mrow><mrow><mi>prog</mi></mrow></msub><mo>:</mo><mi>Prog</mi><mo>→</mo><mi>Myc</mi></mrow></math></span> maps experimental perturbations to induced network transformations. Species and strain variability are expressed as natural transformations between fungal functors, and ecological feedback is captured via an adjunction between sensing and environment modification. Network fusion is identified with pushouts in <span><math><mi>Myc</mi></math></span>, and order effects in exposure sequences are quantified by a local Lie structure and a Baker–Campbell–Hausdorff expansion near the identity program. A minimal example demonstrates how non-commutativity yields experimentally testable quadratic scaling of order asymmetry. The framework provides a structurally explicit and falsifiable basis for analysing compositional perturbations, mixture coupling, robustness limits, and cross-species comparability in fungal systems.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"30 ","pages":"Article 100715"},"PeriodicalIF":1.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148184754","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}