数学最新文献_第3页

Dynamics of weighted shifts on ℓp-sums and c0-sums

IF 1.5 1区数学

Advances in Mathematics Pub Date : 2025-04-05 DOI: 10.1016/j.aim.2025.110250

Quentin Menet , Dimitris Papathanasiou

引用次数: 0

Bifurcations of a Leslie-type model with herd behavior and predator harvesting

IF 5.3 1区数学

Chaos Solitons & Fractals Pub Date : 2025-04-05 DOI: 10.1016/j.chaos.2025.116327

Zhifei Guo, Haiying Yang

引用次数: 0

Normalizing flows as approximations of optimal transport maps via linear-control neural ODEs

IF 1.3 2区数学

Nonlinear Analysis-Theory Methods & Applications Pub Date : 2025-04-05 DOI: 10.1016/j.na.2025.113811

A. Scagliotti , S. Farinelli

{"title":"Normalizing flows as approximations of optimal transport maps via linear-control neural ODEs","authors":"A. Scagliotti , S. Farinelli","doi":"10.1016/j.na.2025.113811","DOIUrl":"10.1016/j.na.2025.113811","url":null,"abstract":"<div><div>In this paper, we consider the problem of recovering the <span><math><msub><mrow><mi>W</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-optimal transport map T between absolutely continuous measures <span><math><mrow><mi>μ</mi><mo>,</mo><mi>ν</mi><mo>∈</mo><mi>P</mi><mrow><mo>(</mo><msup><mrow><mi>R</mi></mrow><mrow><mi>n</mi></mrow></msup><mo>)</mo></mrow></mrow></math></span> as the flow of a linear-control neural ODE, where the control depends only on the time variable and takes values in a finite-dimensional space. We first show that, under suitable assumptions on <span><math><mrow><mi>μ</mi><mo>,</mo><mi>ν</mi></mrow></math></span> and on the controlled vector fields governing the neural ODE, the optimal transport map is contained in the <span><math><msubsup><mrow><mi>C</mi></mrow><mrow><mi>c</mi></mrow><mrow><mn>0</mn></mrow></msubsup></math></span>-closure of the flows generated by the system. Then, we tackle the problem under the assumption that only discrete approximations of <span><math><mrow><msub><mrow><mi>μ</mi></mrow><mrow><mi>N</mi></mrow></msub><mo>,</mo><msub><mrow><mi>ν</mi></mrow><mrow><mi>N</mi></mrow></msub></mrow></math></span> of the original measures <span><math><mrow><mi>μ</mi><mo>,</mo><mi>ν</mi></mrow></math></span> are available: we formulate approximated optimal control problems, and we show that their solutions give flows that approximate the original optimal transport map <span><math><mi>T</mi></math></span>. In the framework of generative models, the approximating flow constructed here can be seen as a ‘Normalizing Flow’, which usually refers to the task of providing invertible transport maps between probability measures by means of deep neural networks. We propose an iterative numerical scheme based on the Pontryagin Maximum Principle for the resolution of the optimal control problem, resulting in a method for the practical computation of the approximated optimal transport map, and we test it on a two-dimensional example.</div></div>","PeriodicalId":49749,"journal":{"name":"Nonlinear Analysis-Theory Methods & Applications","volume":"257 ","pages":"Article 113811"},"PeriodicalIF":1.3,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Nonparametric approaches for direct approximation of the spatial quantiles

IF 2.1 2区数学

Spatial Statistics Pub Date : 2025-04-05 DOI: 10.1016/j.spasta.2025.100896

Pilar García-Soidán , Tomás R. Cotos-Yáñez

{"title":"Nonparametric approaches for direct approximation of the spatial quantiles","authors":"Pilar García-Soidán , Tomás R. Cotos-Yáñez","doi":"10.1016/j.spasta.2025.100896","DOIUrl":"10.1016/j.spasta.2025.100896","url":null,"abstract":"<div><div>The estimation of the spatial quantiles provides information on the thresholds of a spatial variable. This methodology is particularly appealing for its application to data of pollutants, so as to assess their level of risk. A spatial quantile can be approximated through different mechanisms, proposed in the statistics literature, although these approaches suffer from several drawbacks, regarding their lack of optimality or the fact of not leading to direct approximations. Thus, the current work introduces alternative procedures, which try to overcome the aforementioned issues by employing order statistics, similarly as done for independent data. With this aim, the available observations are appropriately transformed to yield a sample of the process at each target site, so that the data obtained are then ordered and used to derive the spatial quantile at the corresponding location. The new methodology can be directly applied to data from processes that are either stationary or that deviate from this condition for a non-constant trend and, additionally, it can be even extended to heteroscedastic data. Simulation studies under different scenarios have been accomplished, whose results show the adequate performance of the proposed estimators. A further step of this research is the application of the new approaches to data of nitrogen dioxide concentrations, to exemplify the potential of the quantile estimates to check the thresholds of a pollutant at a specific moment, as well as their evolution over time.</div></div>","PeriodicalId":48771,"journal":{"name":"Spatial Statistics","volume":"67 ","pages":"Article 100896"},"PeriodicalIF":2.1,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783992","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}

引用次数: 0

Grothendieck polynomials of inverse fireworks permutations

IF 1 3区数学

European Journal of Combinatorics Pub Date : 2025-04-05 DOI: 10.1016/j.ejc.2025.104158

Chen-An (Jack) Chou , Tianyi Yu

引用次数: 0

Quantum codes and irreducible products of characters

IF 1.6 2区数学

Designs, Codes and Cryptography Pub Date : 2025-04-05 DOI: 10.1007/s10623-025-01599-8

Eric Kubischta, Ian Teixeira

引用次数: 0

Asynchronous multimodal PINN pre-train framework based on TransVNet(MPP-TV) and its application in numerical solutions of the Cauchy problem for the Hamilton-Jacobi equation

IF 2.9 2区数学

Computers & Mathematics with Applications Pub Date : 2025-04-05 DOI: 10.1016/j.camwa.2025.03.027

Tianhao Chen , Zeyu Li , Pengbo Xu , Haibiao Zheng

{"title":"Asynchronous multimodal PINN pre-train framework based on TransVNet(MPP-TV) and its application in numerical solutions of the Cauchy problem for the Hamilton-Jacobi equation","authors":"Tianhao Chen , Zeyu Li , Pengbo Xu , Haibiao Zheng","doi":"10.1016/j.camwa.2025.03.027","DOIUrl":"10.1016/j.camwa.2025.03.027","url":null,"abstract":"<div><div>The Hamilton-Jacobi(HJ) equation represents a class of highly nonlinear partial differential equations. Classical numerical techniques, such as finite element methods, face significant challenges when addressing the numerical solutions of such nonlinear HJ equations. However, recent advances in neural network-based approaches, particularly Physics-Informed Neural Networks (PINNs) and neural operator methods, have ushered in innovative paradigms for numerically solving HJ equations. In this work, we leverage the PINN approach, infused with the concept of neural operators. By encoding and extracting features from the discretized images of functions through TransVNet, which is a novel autoencoder architecture proposed in this paper, we seamlessly integrate Hamiltonian information into PINN training, thereby establishing a novel scientific computation framework. Additionally, we incorporate the vanishing viscosity method, introducing viscosity coefficients in our model, which equips our model to tackle potential singularities in nonlinear HJ equations. These attributes signify that our MPP-TV framework paves new avenues and insights for the generalized solutions of nonlinear HJ equations.</div></div>","PeriodicalId":55218,"journal":{"name":"Computers & Mathematics with Applications","volume":"187 ","pages":"Pages 203-230"},"PeriodicalIF":2.9,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777485","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}

引用次数: 0

Time series analysis of wildfire propagation in Chile: A complex networks approach

IF 5.3 1区数学

Chaos Solitons & Fractals Pub Date : 2025-04-05 DOI: 10.1016/j.chaos.2025.116347

Iván Gallo-Méndez , Jaime Clark , Denisse Pastén

{"title":"Time series analysis of wildfire propagation in Chile: A complex networks approach","authors":"Iván Gallo-Méndez , Jaime Clark , Denisse Pastén","doi":"10.1016/j.chaos.2025.116347","DOIUrl":"10.1016/j.chaos.2025.116347","url":null,"abstract":"<div><div>Wildfires are a recurrent and devastating phenomenon that has expanded in Chile and various places worldwide, with complex propagation patterns influenced by environmental, climatic, and anthropogenic factors. In this study, we employ a complex network framework to analyze the temporal and spatial dynamics of fire propagation throughout Chile. Using publicly available data on wildfires, including their locations and dates of occurrence, we map the position and timing of events onto an undirected spatial complex network to characterize fire propagation in Chile’s central and southern zones from a multifractal point of view. We construct a time series associated with the connectivity of nodes, where each event is assigned to a node by position match. Traversing the network sequentially, based on the date and time of the events, generates the connectivity time series, which captures spatiotemporal information. Our analysis demonstrates that the graph exhibits hallmark complexity features. In addition, through an analysis of the connectivity time series, we uncover the multifractal nature of the system. In particular, we show that the central zone exhibits a more remarkable persistence of multifractal behavior than the southern zone, which could provide insights into the underlying dynamics of the system and be valuable for identifying regions with heightened structural or temporal complexity. We expect our findings will contribute to understanding the spatial heterogeneity of fire distribution in Chile and serve as a precedent for future research.</div></div>","PeriodicalId":9764,"journal":{"name":"Chaos Solitons & Fractals","volume":"196 ","pages":"Article 116347"},"PeriodicalIF":5.3,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Firing modes of a memristive complex-valued FHN neuron

IF 5.3 1区数学

Chaos Solitons & Fractals Pub Date : 2025-04-05 DOI: 10.1016/j.chaos.2025.116372

Huaqing Nie , Jian Liu , Dan Wang , Fangfang Zhang , Wenjing Wang

{"title":"Firing modes of a memristive complex-valued FHN neuron","authors":"Huaqing Nie , Jian Liu , Dan Wang , Fangfang Zhang , Wenjing Wang","doi":"10.1016/j.chaos.2025.116372","DOIUrl":"10.1016/j.chaos.2025.116372","url":null,"abstract":"<div><div>Memristors have been extensively integrated into neurons as key elements for emulating electromagnetic radiation (EMR). The complex firing patterns triggered by external magnetic field is a hot topic in neuronal dynamics. By integrating a specially designed memristor into a complex-valued FitzHugh–Nagumo (CV-FHN) neuron model to emulate external magnetic induction current, we have developed a novel neuromorphic system. Our findings reveal that hidden scroll-controlled chaotic attractors can be generated from the neuromorphic system through adjustment of the memristor parameter, while the offset of heterogeneous coexisting attractors in the phase space can be boosted by modifying the initial conditions of the memristor. Moreover, the Hamilton energy function of the neuron is calculated by using Helmholtz’s theorem. The results of Hamilton energy analysis indicate that various hidden firing patterns, including hidden chaotic spiking and even hyperchaotic bursting, can be modulated by external stimuli. In this work, the introduction of memristor into CV-FHN neuron significantly enhances the chaos complexity of neuronal firing dynamics of the original neuron. This memristive CV-FHN neuron serves as a promising candidate for constituting large-scale functional neural network.</div></div>","PeriodicalId":9764,"journal":{"name":"Chaos Solitons & Fractals","volume":"196 ","pages":"Article 116372"},"PeriodicalIF":5.3,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Guaranteeing fairness and efficiency under budget constraints 在预算限制下保证公平和效率

IF 1 4区数学

Journal of Combinatorial Optimization Pub Date : 2025-04-05 DOI: 10.1007/s10878-025-01275-6

Yuanyuan Wang, Xin Chen, Qizhi Fang, Qingqin Nong, Wenjing Liu

{"title":"Guaranteeing fairness and efficiency under budget constraints","authors":"Yuanyuan Wang, Xin Chen, Qizhi Fang, Qingqin Nong, Wenjing Liu","doi":"10.1007/s10878-025-01275-6","DOIUrl":"https://doi.org/10.1007/s10878-025-01275-6","url":null,"abstract":"<p>We study the problem of how to fairly and efficiently allocate indivisible items (goods) to agents under budget constraints. Each item has a specific size, and each agent has a budget that limits the total size of the items received. To better explore efficiency, we introduce the concept of tightness, where all agents are tight. An agent is considered as tight if adding any unallocated item to her bundle would exceed her budget. Interestingly, we observe that all individual optimal (IO) allocations, which contain Pareto optimal (PO) allocations, can be extended into a tight allocation while maintaining the values of the agents’ bundles. We achieve an overall negative result for general even identical or binary valuations: there exists no allocation meeting both tightness and envy-freeness up to any item (EFX), and even relaxing it to any desired approximate EFX has been proven to be impossible. However, for single-valued valuations, we illustrate that an EFX and tight (or IO) allocation always exist, and it can be computed using a polynomial algorithm. For single-valued valuations, we establish the existence of 1/2-EFX and PO allocations, with the approximation ratio being the best possible. To further our efforts to study fairness and efficiency, we introduce a relaxed concept of tightness, partial tightness (PT), in which only the unenvied agents are tight. We find that 1/2-EFX and PT allocations are achievable by providing a pseudo-polynomial time algorithm. When agents’ budgets are identical, we can compute a 1/2-EFX and PT allocation in polynomial time.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":"538 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143782635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0