Pub Date : 2026-01-28DOI: 10.1016/j.matcom.2026.01.029
Walid Remili , Samad Noeiaghdam
This paper introduces a high-order numerical method for the solution of nonlinear Volterra–Hammerstein integral equations (NVHIEs) with smooth and weakly singular kernels, based on the collocation approach. The proposed method employs a collocation scheme with shifted Chebyshev polynomials (SCPs), combined with an appropriate variable transformation, to reduce the integral equation to a nonlinear algebraic system. We rigorously analyze the convergence properties of the collocation method, establishing its theoretical validity and proving a specific convergence rate of , which highlights the rigor and efficiency of the approach. To ensure reliable error control and stability, we integrate the CESTAC (Contrôle et Estimation Stochastique des Arrondis de Calculs) method and the CADNA (Control of Accuracy and Debugging for Numerical Applications) library, providing a unified framework that identifies numerical instabilities (self-validation, mathematical, branching, and intrinsic) while also determining the optimal step size, optimal approximation, and optimal error. Several numerical examples are presented and compared with existing methods to illustrate the enhanced efficiency and accuracy of our approach.
本文介绍了一种基于配点法求解光滑弱奇异核非线性Volterra-Hammerstein积分方程的高阶数值方法。该方法采用平移切比雪夫多项式(SCPs)搭配方案,结合适当的变量变换,将积分方程简化为非线性代数系统。我们严格分析了该方法的收敛性,建立了该方法的理论有效性,并证明了其特定的收敛速度为0 (N3/4−m),从而突出了该方法的严谨性和有效性。为了确保可靠的误差控制和稳定性,我们集成了CESTAC (Contrôle et Estimation Stochastique des Arrondis de Calculs)方法和CADNA(精度控制和数值应用调试)库,提供了一个统一的框架,可以识别数值不稳定性(自我验证、数学、分支和内在),同时确定最佳步长、最佳近似和最佳误差。给出了几个数值算例,并与现有方法进行了比较,以说明本文方法提高了效率和精度。
{"title":"Shifted Chebyshev collocation with CESTAC-CADNA-based instability detection for nonlinear Volterra–Hammerstein integral equations","authors":"Walid Remili , Samad Noeiaghdam","doi":"10.1016/j.matcom.2026.01.029","DOIUrl":"10.1016/j.matcom.2026.01.029","url":null,"abstract":"<div><div>This paper introduces a high-order numerical method for the solution of nonlinear Volterra–Hammerstein integral equations (NVHIEs) with smooth and weakly singular kernels, based on the collocation approach. The proposed method employs a collocation scheme with shifted Chebyshev polynomials (SCPs), combined with an appropriate variable transformation, to reduce the integral equation to a nonlinear algebraic system. We rigorously analyze the convergence properties of the collocation method, establishing its theoretical validity and proving a specific convergence rate of <span><math><mrow><mi>O</mi><mrow><mo>(</mo><msup><mrow><mi>N</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>4</mn><mo>−</mo><mi>m</mi></mrow></msup><mo>)</mo></mrow></mrow></math></span>, which highlights the rigor and efficiency of the approach. To ensure reliable error control and stability, we integrate the CESTAC (Contrôle et Estimation Stochastique des Arrondis de Calculs) method and the CADNA (Control of Accuracy and Debugging for Numerical Applications) library, providing a unified framework that identifies numerical instabilities (self-validation, mathematical, branching, and intrinsic) while also determining the optimal step size, optimal approximation, and optimal error. Several numerical examples are presented and compared with existing methods to illustrate the enhanced efficiency and accuracy of our approach.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"246 ","pages":"Pages 60-77"},"PeriodicalIF":4.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-28DOI: 10.1016/S0378-4754(26)00037-6
{"title":"IMACS Calendar of Events","authors":"","doi":"10.1016/S0378-4754(26)00037-6","DOIUrl":"10.1016/S0378-4754(26)00037-6","url":null,"abstract":"","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"244 ","pages":"Page 265"},"PeriodicalIF":4.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-28DOI: 10.1016/S0378-4754(26)00036-4
{"title":"News of IMACS","authors":"","doi":"10.1016/S0378-4754(26)00036-4","DOIUrl":"10.1016/S0378-4754(26)00036-4","url":null,"abstract":"","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"244 ","pages":"Page 264"},"PeriodicalIF":4.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-24DOI: 10.1016/j.matcom.2026.01.027
Vikash Sharma, Vineet Kumar Singh
In this manuscript, we investigate various properties of the Generalized time fractional derivative (GTFD). We establish several regularity results and derive bounds in specific spaces like that characterize the behavior of the GTFD operator. Furthermore, we propose an efficient hybrid computational approximation to approximate the GTFD of order , applicable to smooth and non-smooth solutions. This approximation is based on a Newton interpolation polynomial of arbitrary finite degree. The role of scale and weight functions in influencing the local truncation error and convergence order is thoroughly analyzed, with numerical experiments providing validation of these theoretical insights. The proposed approximation is further utilized to construct a computational scheme for solving the general time fractional diffusion equation (GTFDE), for which we rigorously establish uniqueness and convergence, while stability is proven specifically for linear interpolation. Numerical examples are utilized to verify that our scheme is more efficient compared to the existing schemes (Stynes et al., 2017, Z. wang, 2025 and Xu et al., 2013). Without loss of generality, numerical results are presented for linear and quadratic interpolation, confirming the approximation’s accuracy and consistency with theoretical predictions.
本文研究了广义时间分数阶导数(GTFD)的各种性质。我们建立了几个正则性结果,并在C1,W1,1等特定空间中推导了表征GTFD算子行为的界。此外,我们提出了一种有效的混合计算近似来近似阶α∈(0,1)的GTFD,适用于光滑和非光滑解。这种近似是基于任意有限次的牛顿插值多项式。深入分析了尺度函数和权函数对局部截断误差和收敛阶的影响,并通过数值实验验证了这些理论见解。进一步利用所提出的近似构造了求解一般时间分数扩散方程(GTFDE)的计算格式,并严格建立了该格式的唯一性和收敛性,同时证明了该格式在线性插值下的稳定性。数值算例验证了我们的方案比现有方案更高效(Stynes et al., 2017, Z. wang, 2025 and Xu et al., 2013)。在不丧失一般性的情况下,给出了线性和二次插值的数值结果,证实了近似的准确性和与理论预测的一致性。
{"title":"Approximation of generalized time fractional derivatives: Error analysis via scale and weight functions","authors":"Vikash Sharma, Vineet Kumar Singh","doi":"10.1016/j.matcom.2026.01.027","DOIUrl":"10.1016/j.matcom.2026.01.027","url":null,"abstract":"<div><div>In this manuscript, we investigate various properties of the Generalized time fractional derivative (GTFD). We establish several regularity results and derive bounds in specific spaces like <span><math><mrow><msup><mrow><mi>C</mi></mrow><mrow><mn>1</mn></mrow></msup><mo>,</mo><msup><mrow><mi>W</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>1</mn></mrow></msup></mrow></math></span> that characterize the behavior of the GTFD operator. Furthermore, we propose an efficient hybrid computational approximation to approximate the GTFD of order <span><math><mrow><mi>α</mi><mo>∈</mo><mrow><mo>(</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span>, applicable to smooth and non-smooth solutions. This approximation is based on a Newton interpolation polynomial of arbitrary finite degree. The role of scale and weight functions in influencing the local truncation error and convergence order is thoroughly analyzed, with numerical experiments providing validation of these theoretical insights. The proposed approximation is further utilized to construct a computational scheme for solving the general time fractional diffusion equation (GTFDE), for which we rigorously establish uniqueness and convergence, while stability is proven specifically for linear interpolation. Numerical examples are utilized to verify that our scheme is more efficient compared to the existing schemes (Stynes et al., 2017, Z. wang, 2025 and Xu et al., 2013). Without loss of generality, numerical results are presented for linear and quadratic interpolation, confirming the approximation’s accuracy and consistency with theoretical predictions.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"246 ","pages":"Pages 1-24"},"PeriodicalIF":4.4,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-23DOI: 10.1016/j.matcom.2026.01.028
Xiaoquan Kong , Ruizhi Yang
This study focuses on the Lymantria dispar-Great tit ecosystem, constructing a Filippov model with double Allee effects and proposing an integrated control strategy based on two thresholds for both pest density and natural enemy abundance. Through stability analysis of equilibria and sliding mode dynamics, the study reveals the existence of multiple sliding segments and pseudo-equilibria in the system, which can induce rich sliding bifurcation behaviors. Further investigation uncovers complex dynamical patterns under different threshold conditions, including sliding bifurcations as well as local and global bifurcations. Partial Rank Correlation Coefficient based global sensitivity analysis identifies key parameters influencing the system dynamics. The research demonstrates that appropriate setting of these two thresholds is crucial for achieving sustainable control of Lymantria dispar, while the synergistic effect of biological control and natural enemy release is essential for maintaining ecological balance.
本文以Lymantria - great tit生态系统为研究对象,构建了具有双Allee效应的Filippov模型,提出了基于害虫密度和天敌丰度两个阈值的综合防治策略。通过平衡态和滑模动力学稳定性分析,揭示了系统中存在多个滑动段和伪平衡态,从而引发丰富的滑动分岔行为。进一步的研究揭示了不同阈值条件下复杂的动力学模式,包括滑动分岔以及局部和全局分岔。基于偏秩相关系数的全局敏感性分析识别出影响系统动力学的关键参数。研究表明,合理设置这两个阈值对于实现野毒的可持续控制至关重要,而生物防治与天敌释放的协同效应对于维持生态平衡至关重要。
{"title":"Dynamics analysis of a Filippov Lymantria dispar-Great tit model with double Allee effects and two-thresholds control","authors":"Xiaoquan Kong , Ruizhi Yang","doi":"10.1016/j.matcom.2026.01.028","DOIUrl":"10.1016/j.matcom.2026.01.028","url":null,"abstract":"<div><div>This study focuses on the Lymantria dispar-Great tit ecosystem, constructing a Filippov model with double Allee effects and proposing an integrated control strategy based on two thresholds for both pest density and natural enemy abundance. Through stability analysis of equilibria and sliding mode dynamics, the study reveals the existence of multiple sliding segments and pseudo-equilibria in the system, which can induce rich sliding bifurcation behaviors. Further investigation uncovers complex dynamical patterns under different threshold conditions, including sliding bifurcations as well as local and global bifurcations. Partial Rank Correlation Coefficient based global sensitivity analysis identifies key parameters influencing the system dynamics. The research demonstrates that appropriate setting of these two thresholds is crucial for achieving sustainable control of Lymantria dispar, while the synergistic effect of biological control and natural enemy release is essential for maintaining ecological balance.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"246 ","pages":"Pages 25-43"},"PeriodicalIF":4.4,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.matcom.2026.01.026
Pradip Debnath
We present a novel extension of the Caristi-type fixed point theorem recently established by Zubelevich (2025) for single-valued mappings on complete semi-metric spaces to the multivalued setting. Specifically, we prove that, in a complete semi-metric space , if a set-valued mapping satisfies a generalized Caristi-type inequality involving a family of lower semi-continuous, bounded-from-below functions and a semi-metric structure, then admits a fixed point. Our approach constructs a suitable selection from the multivalued map and applies Zubelevich’s partial order method in conjunction with Zorn’s lemma to ensure the existence of a fixed point. Furthermore, we establish a multivalued counterpart to Zubelevich’s noncompactness theorem: if one of the associated potential functions fails to attain its minimum, then the fixed point set of is necessarily noncompact. These results provide the first known multivalued Caristi-type fixed point framework for semi-metric spaces, unifying and generalizing prior work in both metric and topological vector space settings. The results are further validated by a numerical simulation showing convergence of iterates under deterministic selections.
{"title":"Multivalued extension of the Caristi-type theorem in semi-metric spaces and its numerical simulation","authors":"Pradip Debnath","doi":"10.1016/j.matcom.2026.01.026","DOIUrl":"10.1016/j.matcom.2026.01.026","url":null,"abstract":"<div><div>We present a novel extension of the Caristi-type fixed point theorem recently established by Zubelevich (2025) for single-valued mappings on complete semi-metric spaces to the multivalued setting. Specifically, we prove that, in a complete semi-metric space <span><math><mi>R</mi></math></span>, if a set-valued mapping <span><math><mrow><mi>F</mi><mo>:</mo><mi>R</mi><mo>→</mo><msup><mrow><mn>2</mn></mrow><mrow><mi>R</mi></mrow></msup></mrow></math></span> satisfies a generalized Caristi-type inequality involving a family of lower semi-continuous, bounded-from-below functions and a semi-metric structure, then <span><math><mi>F</mi></math></span> admits a fixed point. Our approach constructs a suitable selection from the multivalued map and applies Zubelevich’s partial order method in conjunction with Zorn’s lemma to ensure the existence of a fixed point. Furthermore, we establish a multivalued counterpart to Zubelevich’s noncompactness theorem: if one of the associated potential functions fails to attain its minimum, then the fixed point set of <span><math><mi>F</mi></math></span> is necessarily noncompact. These results provide the first known multivalued Caristi-type fixed point framework for semi-metric spaces, unifying and generalizing prior work in both metric and topological vector space settings. The results are further validated by a numerical simulation showing convergence of iterates under deterministic selections.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 325-336"},"PeriodicalIF":4.4,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.matcom.2026.01.025
Daifeng Duan , Biao Liu , Junjie Wei
We investigate the effects of periodic boundary conditions on a nonlocal Holling–Tanner model defined on a square domain. A top-hat kernel function with finite support is employed to characterize nonlocal interactions, which we further adapt to accommodate periodic boundary conditions. Subsequently, we derive the Turing and spatiotemporal Hopf bifurcation curves and conduct numerical simulations across the parameter ranges delineated by these curves. Our findings demonstrate substantial differences in spatiotemporal patterns between the square domain and the one-dimensional case, including squares, stripes, mixed states, irregular spot-like hexagonal patterns, and coexistence states of three-stripes and spots. These observed patterns exhibit remarkable consistency with both chemical experimental results and the skin pigmentation patterns of fish, thereby offering valuable theoretical insights and predictive frameworks for understanding spatiotemporal patterns in chemical and biological systems.
{"title":"Pattern formation of the Holling–Tanner model with top-hat kernel functions on square domains","authors":"Daifeng Duan , Biao Liu , Junjie Wei","doi":"10.1016/j.matcom.2026.01.025","DOIUrl":"10.1016/j.matcom.2026.01.025","url":null,"abstract":"<div><div>We investigate the effects of periodic boundary conditions on a nonlocal Holling–Tanner model defined on a square domain. A top-hat kernel function with finite support is employed to characterize nonlocal interactions, which we further adapt to accommodate periodic boundary conditions. Subsequently, we derive the Turing and spatiotemporal Hopf bifurcation curves and conduct numerical simulations across the parameter ranges delineated by these curves. Our findings demonstrate substantial differences in spatiotemporal patterns between the square domain and the one-dimensional case, including squares, stripes, mixed states, irregular spot-like hexagonal patterns, and coexistence states of three-stripes and spots. These observed patterns exhibit remarkable consistency with both chemical experimental results and the skin pigmentation patterns of fish, thereby offering valuable theoretical insights and predictive frameworks for understanding spatiotemporal patterns in chemical and biological systems.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 366-383"},"PeriodicalIF":4.4,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we propose and analyze a finite element coupled multiscale finite element method (FEM-MsFEM) for an interface-coupled parabolic problem. The problem involves a coefficient with multiscale characteristics in one region and in the other region without such feature. Our algorithm consists of two main steps: first, solving for the multiscale basis functions in the multiscale region via parallel computation; and second, decoupling the interface-coupled parabolic problem using a data-passing partitioned scheme. This approach allows for the problem to be solved on relatively coarse grids, thereby reducing computational costs. Under suitable assumptions for the multiscale coefficient, we establish the unconditional stability and provide error estimates for the algorithm. The effectiveness of our method is demonstrated through several numerical experiments.
{"title":"FEM-MsFEM for an interface-coupled parabolic problem","authors":"Jiaping Yu , Wenhan Zhang , Ren Zhao , Haibiao Zheng","doi":"10.1016/j.matcom.2026.01.023","DOIUrl":"10.1016/j.matcom.2026.01.023","url":null,"abstract":"<div><div>In this paper, we propose and analyze a finite element coupled multiscale finite element method (FEM-MsFEM) for an interface-coupled parabolic problem. The problem involves a coefficient with multiscale characteristics in one region and in the other region without such feature. Our algorithm consists of two main steps: first, solving for the multiscale basis functions in the multiscale region via parallel computation; and second, decoupling the interface-coupled parabolic problem using a data-passing partitioned scheme. This approach allows for the problem to be solved on relatively coarse grids, thereby reducing computational costs. Under suitable assumptions for the multiscale coefficient, we establish the unconditional stability and provide error estimates for the algorithm. The effectiveness of our method is demonstrated through several numerical experiments.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 409-427"},"PeriodicalIF":4.4,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we analyze the dynamics of an eco-epidemiological amensalism model involving three species, where the first species exhibits a weak Allee effect. In contrast, the second and third species are subjected to proportional harvesting. The proposed model assumes that the disease only affects the second species while the first species remains unaffected. We consider harvesting as a control parameter for both disease and amensalism dynamics. The amensalism functional response is modeled using the Holling type II response, while disease transmission follows a saturation incidence rate. Our primary mathematical objectives are to analyze the effects of the Allee parameter and harvesting on the system’s dynamics. By treating key parameters as bifurcation and threshold variables, the stability of all equilibria and the associated bifurcations are analyzed. The model exhibits a degenerate Bogdanov–Takens (BT), two saddle–node and three transcritical bifurcations. Conditions for both extinction and persistence are derived in terms of the harvesting rate. A critical threshold of harvesting is identified, beyond which the diseased species declines and the disease-free equilibrium becomes stable. Our findings reveal an upper limit of harvesting within which all species can coexist. However, the coexistence of all three species depends on initial conditions, leading to bistability. Notably, the Allee effect acts only on the first species, underlies the occurrence of a saddle–node bifurcation and eliminating equilibria for a certain parameter range, while leaving the other two species unaffected. These results provide quantitative insights into the interplay between the Allee effect and harvesting in shaping species coexistence and system dynamics.
{"title":"Dynamic interplay of Allee effect and harvesting in a diseased amensalism model: Unraveling ecological complexity","authors":"Sarita Bugalia , Sandeep Kumar , Jai Prakash Triapthi , Maia Martcheva","doi":"10.1016/j.matcom.2026.01.021","DOIUrl":"10.1016/j.matcom.2026.01.021","url":null,"abstract":"<div><div>In this paper, we analyze the dynamics of an eco-epidemiological amensalism model involving three species, where the first species exhibits a weak Allee effect. In contrast, the second and third species are subjected to proportional harvesting. The proposed model assumes that the disease only affects the second species while the first species remains unaffected. We consider harvesting as a control parameter for both disease and amensalism dynamics. The amensalism functional response is modeled using the Holling type II response, while disease transmission follows a saturation incidence rate. Our primary mathematical objectives are to analyze the effects of the Allee parameter and harvesting on the system’s dynamics. By treating key parameters as bifurcation and threshold variables, the stability of all equilibria and the associated bifurcations are analyzed. The model exhibits a degenerate Bogdanov–Takens (BT), two saddle–node and three transcritical bifurcations. Conditions for both extinction and persistence are derived in terms of the harvesting rate. A critical threshold of harvesting is identified, beyond which the diseased species declines and the disease-free equilibrium becomes stable. Our findings reveal an upper limit of harvesting within which all species can coexist. However, the coexistence of all three species depends on initial conditions, leading to bistability. Notably, the Allee effect acts only on the first species, underlies the occurrence of a saddle–node bifurcation and eliminating equilibria for a certain parameter range, while leaving the other two species unaffected. These results provide quantitative insights into the interplay between the Allee effect and harvesting in shaping species coexistence and system dynamics.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 295-324"},"PeriodicalIF":4.4,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-17DOI: 10.1016/j.matcom.2026.01.015
B. Takacs
In this paper, nonstandard multistep methods are considered. It is shown that under some (sufficient and necessary) conditions, these methods attain the same order as their standard counterpart — to prove this statement, a nonstandard version of Taylor’s series is constructed. The preservation of some qualitative properties (boundedness, the linear combination of the components, and a property similar to monotonicity) is also proven for all step sizes. The methods are applied to a one-dimensional equation and a system of equations, in which the numerical experiments confirm the theoretical results.
{"title":"An insight on some properties of high order nonstandard linear multistep methods","authors":"B. Takacs","doi":"10.1016/j.matcom.2026.01.015","DOIUrl":"10.1016/j.matcom.2026.01.015","url":null,"abstract":"<div><div>In this paper, nonstandard multistep methods are considered. It is shown that under some (sufficient and necessary) conditions, these methods attain the same order as their standard counterpart — to prove this statement, a nonstandard version of Taylor’s series is constructed. The preservation of some qualitative properties (boundedness, the linear combination of the components, and a property similar to monotonicity) is also proven for all step sizes. The methods are applied to a one-dimensional equation and a system of equations, in which the numerical experiments confirm the theoretical results.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 337-365"},"PeriodicalIF":4.4,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}