摘要：
Abstract Forecasting equity risk premium is notoriously difficult due to a mass of data noise in the raw series and the absence of clear tendency. Using the monthly S&P 500 excess returns from 1927:01 to 2018:12, we first de‐noise the in‐sample original returns series via wavelet method to capture the basic trend of equity risk premium, and then propose forecasting models to obtain one‐step forward out‐of‐sample predicted values based on the de‐noised returns. Our new models can provide substantially superior out‐of‐sample performance compared with other competing models and the historical average. Sizeable economic gains can be realized by a mean–variance investor if they allocate their asset through the new approach. Our findings are robust under different settings from both statistical and economic perspectives.
摘要：
Pawlak conflict analysis focuses on three-valued ratings of a set of agents on a set of issues, in which the three values +, 0, and - indicate, respectively, that an agent is positive, neutral, and negative about an issue. According to their shared ratings, we can form different types of agent coalitions and, similarly, different types of issue bundles (i.e., families of issues to be considered together). The main objective of this paper is to introduce and investigate connections of agent coalitions and issue bundles from Wille formal concept analysis perspectives. By interpreting a three-valued rating table as four different formal contexts, we introduce four types of agent coalitions, namely, support, non-opposition, opposition, and non-support coalitions, the corresponding four types of issue bundles, and four lattices of coalition-bundle couplings. The lattices reveal structural information of agents and issues in a conflict situation. To demonstrate the usefulness of the proposed model, we analyze the problem of development planning of the Gansu Province of China.(c) 2022 Elsevier Inc. All rights reserved.
摘要：
This paper considers a single-layer fourth order quasi-geostrophic equation in two-dimensional case. We prove the existence and uniqueness of global smooth solution to the Cauchy problem of this equation by using energy estimate. We also establish a new estimate for the nonlinear term and obtain decay estimates of the solution in
$$L^{2}$$
.
期刊：
DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS,2023年16(11):2980-3013 ISSN：1078-0947
通讯作者：
Lin, Q
作者机构：
[Zhang, Fubao; Cai, Li] Southeast Univ, Sch Math, Nanjing 210096, Peoples R China.;[Lin, Qiang] Changsha Univ Sci & Technol, Sch Math & Stat, Changsha 410004, Peoples R China.;[Zhang, Fubao] Southeast Univ, Chengxian Coll, Nanjing 210088, Peoples R China.;[Lin, Qiang; Cai, Li] Univ Craiova, Dept Math, Craiova 200585, Romania.;[Lin, Qiang; Cai, Li] China Romania Res Ctr Appl Math, Craiova, Romania.
通讯机构：
[Lin, Q ] C;Changsha Univ Sci & Technol, Sch Math & Stat, Changsha 410004, Peoples R China.;Univ Craiova, Dept Math, Craiova 200585, Romania.;China Romania Res Ctr Appl Math, Craiova, Romania.
关键词：
Coupled Kirchhoff system;high energy solutions;Linking theorem;Nehari manifold method;topological degree theory
摘要：
In this paper, we consider the coupled Kirchhoff system in subcrit-ical case and critical case. For subcritical case, we first study the least energy of coupled Kirchhoff system and the limit system by using the Nehari manifold method and exclude the existence of semi-trivial solutions. Then we improve the global compactness lemma of coupled Kirchhoff system to overcome the loss of compactness. Combining with the linking theorem and topological de-gree, we construct a Palais-Smale sequence in the high energy level and prove the existence of high energy positive solutions. Moreover, the results of the subcritical case are extended to the critical case.
期刊：
EUROPEAN JOURNAL OF FINANCE,2023年29(9):949-976 ISSN：1351-847X
通讯作者：
Xin Yang
作者机构：
[Yang, Xin; Deng, Yunke; Huang, Chuangxia] Changsha Univ Sci & Technol, Sch Math & Stat, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha, Peoples R China.;[Yang, Xin; Huang, Chuangxia] Changsha Univ Sci & Technol, Sch Econ & Management, Changsha, Peoples R China.;[Deng, Yunke] Univ Chinese Acad Sci, cSch Econ & Management, Beijing, Peoples R China.;[Yang, Xiaoguang] Chinese Acad Sci, Acad Math & Syst Sci, Beijing, Peoples R China.;[Cao, Jinde] Southeast Univ, Sch Math, Nanjing, Peoples R China.
通讯机构：
[Xin Yang] S;School of Mathematics and Statistics, Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science and Technology, Changsha, People’s Republic of China<&wdkj&>School of Economics & Management, Changsha University of Science and Technology, Changsha, People’s Republic of China
关键词：
Financial crisis;complex network;Laplacian energy;network structure;seasonal-trend decomposition procedure based on loess (STL)
摘要：
In this paper, we study the variable-order generalized time fractional Oldroyd-B fluid model, use the reduced order method and the L2-1 Sigma method to establish the differential format with second-order accuracy, prove the stability and conver-gence of the format, and give numerical examples to illustrate the effectiveness of the differential format.
期刊：
Mathematical Methods in the Applied Sciences,2023年47(6):- ISSN：0170-4214
通讯作者：
Zhang, JJ
作者机构：
[Li, Jing; Zhao, Haoyu] Changsha Univ Sci & Technol, Sch Math & Stat, Changsha, Hunan, Peoples R China.;[Zhao, Haoyu; Zhang, Jingjun] Jiaxing Univ, Coll Data Sci, Jiaxing, Zhejiang, Peoples R China.;[Zhang, Jingjun] Jiaxing Univ, Coll Data Sci, Jiaxing 314001, Zhejiang, Peoples R China.
通讯机构：
[Zhang, JJ ] J;Jiaxing Univ, Coll Data Sci, Jiaxing 314001, Zhejiang, Peoples R China.
关键词：
Fourier-splitting method;quasi-geostrophic model;upper and lower bounds
摘要：
This paper studies the fractional quasi‐geostrophic equation with modified dissipation term. We first prove the existence and uniqueness of smooth solution of the fractional quasi‐geostrophic equation by using the regularization method. Then, utilizing the Fourier‐splitting method, we obtain the long‐time behavior of the solution. More precisely, we show that under suitable assumptions on the initial data, for any multi‐index γ,m≥4$$ \gamma, m\ge 4 $$ and α∈12,1$$ \alpha \in \left(\frac{1}{2},1\right) $$, the solution ψ$$ \psi $$ satisfies C1(1+t)−1+|γ|2+2α≤∇γψ(·,t)L2≤C2(1+t)−1+|γ|2+2α,|γ|=0,1,…,m−1,t≥1,$$ {C}_1{\left(1&amp;#x0002B;t\right)}&amp;#x0005E;{-\frac{1&amp;#x0002B;\mid \gamma \mid }{2&amp;#x0002B;2\alpha }}\le {\left\Vert {\nabla}&amp;#x0005E;{\gamma}\psi \left(\cdotp, t\right)\right\Vert}_{L&amp;#x0005E;2}\le {C}_2{\left(1&amp;#x0002B;t\right)}&amp;#x0005E;{-\frac{1&amp;#x0002B;\mid \gamma \mid }{2&amp;#x0002B;2\alpha }},\mid \gamma \mid &amp;#x0003D;0,1,\dots, m-1,t\ge 1, $$ and C3(1+t)−1+|γ|2+2α≤||∇γψ(·,t)||L2≤C4(1+t)−|γ|2+2α,|γ|=m,t≥1.$$ {C}_3{\left(1&amp;#x0002B;t\right)}&amp;#x0005E;{-\frac{1&amp;#x0002B;\mid \gamma \mid }{2&amp;#x0002B;2\alpha }}\le {\left\Vert {\nabla}&amp;#x0005E;{\gamma}\psi \Big(\cdotp, t\Big)\right\Vert}_{L&amp;#x0005E;2}\le {C}_4{\left(1&amp;#x0002B;t\right)}&amp;#x0005E;{-\frac{\mid \gamma \mid }{2&amp;#x0002B;2\alpha }},\mid \gamma \mid &amp;#x0003D;m,t\ge 1. $$
关键词：
lacking instantaneous damping;memory;nonclassical diffusion equation;systems;the time-dependent global attractors;unbounded domain
摘要：
In this paper, the asymptotic behavior of nonclassical diffusion equations with time-dependent perturbed parameter and lacking instantaneous damping is considered on whole space Double-struck capital Rn$$ {\mathrm{\mathbb{R}}}<^>n $$. The existence and regularity of time-dependent global attractors are proved by using a new analytical technique. It is remarkable that there is not any restriction on the upper growth of the nonlinearity f$$ f $$. The result obtained essentially extends and improves earlier ones.
摘要：
Nowadays, the researches of conflict analysis are increasing with the development of three-way decisions, and three-way decisions with rankings and reference tuples provides new perspectives for conflict analysis. In this paper, we first divide a whole set of issues into a bundle of supported issues and a bundle of non-supported issues, and a bundle of opposed issues and a bundle of non-opposed issues, respectively, from the perspectives of support and opposition. Accordingly, we give two ranking orders and two reference tuples. Then, we put forward alliance and conflict measures by considering weights of issues, and develop models of three-way conflict analysis with ideas of rankings and reference tuples. Finally, we show how to compute the alliance, neutral and conflict coalitions with the proposed models. It provides an attempt to study conflict problems with thoughts of rankings and reference tuples.
摘要：
The aim of this article is to study the relative Auslander bijection in n-exangulated categories. More precisely, we introduce the notion of generalized Auslander-Reiten-Serre duality and exploit a bijection triangle, which involves the generalized Auslander-Reiten-Serre duality and the restricted Auslander bijection relative to the subfunctor. As an application, this result generalizes the work by Zhao in extriangulated categories.
通讯机构：
[Wang, C ] C;Changsha Univ Sci & Technol, Sch Math & Stat, Changsha 410114, Peoples R China.
关键词：
filtering evidence;GAT;Natural language inference;program-like evidence;table-based fact verification
摘要：
Table-based fact verification requests parsing table and statement structure and performing numerical and logical reasoning. Previous methods may select erroneous programs and ignore the interpretability of table-based fact verification. Thus, we propose a double graph attention network reasoning method based on filtering and program-like evidence (DGMFP). In detail, we initially obtain the filtering evidence based on tables and the program-like evidence based on logical forms to incorporate the semantic and symbolic information of evidence. Then, we construct an evidence graph with statement-evidence pairs as nodes and use the kernel in graph neural network to conduct more fine-grained joint reasoning and improve the interpretability of table-based fact verification. We also construct a connected graph with all entities and functions in the program-like evidence as nodes and use the graph attention network (GAT) to capture more fine-grained relationships within the program-like evidence. Finally, we connect the outputs of two GAT models and BERT model to predict labels. Experimental results on TABFACT show that DGMFP outperforms all baselines with 76.1% accuracy. Ablation studies further indicate that constructed two graphs, filtering evidence, and program-like evidence play an important role in better understanding the semi-structured table.
期刊：
International Review of Economics & Finance,2023年83:421-450 ISSN：1059-0560
通讯作者：
Zhifeng Dai
作者机构：
[Dai, Zhifeng; Zhu, Haoyang] Changsha Univ Sci & Technol, Coll Math & Stat, Hunan Prov Key Lab Math Modeling & Anal Engn, Changsha 410114, Hunan, Peoples R China.
通讯机构：
[Zhifeng Dai] C;College of Mathematics and Statistics, Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science and Technology, Hunan, 410114, China
摘要：
Using daily return, realized volatility, realized skewness and realized kurtosis as risk proxies, we analyze the risk spillovers among crude oil, gold, economic policy uncertainty (EPU) and four Chinese financial sectors including bank, trust, insurance and security under different market conditions. Our analysis spans from January 10, 2008 to June 30, 2020 and is based on the combination of quantile VAR model and time-varying parameter vector autoregressive (TVP-VAR) model based on generalized forecast error variance decomposition. We find that: (1) The risk spillovers of the four risk proxies under 0.01-quantile and 0.99-quantile are much larger than those under mean and median (0.5-quantile); (2) The four risk proxies capture different infor-mation of the systemic shocks; (3) Term spread and credit spread have significant forecasting power on the total return spillovers and the total volatility spillovers.
期刊：
Mathematical Methods in the Applied Sciences,2023年46(5):5267-5285 ISSN：0170-4214
通讯作者：
Wenjie Li<&wdkj&>Wenjie Li Wenjie Li Wenjie Li
作者机构：
[Li, Wenjie] Kunming Univ Sci & Technol, Dept Syst & Appl Math, Kunming 650093, Yunnan, Peoples R China.;[Ji, Jinchen] Univ Technol Sydney Broadway, Sch Mech & Mechatron Engn, Ultimo, NSW, Australia.;[Huang, Lihong] Changsha Univ, Coll Math & Comp Sci, Changsha, Peoples R China.;[Huang, Lihong] Changsha Univ Sci & Technol, Sch Math & Stat, Changsha, Peoples R China.;[Cai, Zuowei] Hunan Womens Univ, Dept Informat Technol, Changsha, Peoples R China.
通讯机构：
[Wenjie Li; Wenjie Li Wenjie Li Wenjie Li] D;Department of Systems and Applied Mathematics, Kunming University of Science and Technology, Kunming, China
摘要：
This paper employs a discontinuous temporary immunity control to obtain the periodic orbit for a class of delayed malicious signal transmission model in wireless sensor networks under the framework of differential inclusion. The positivity and boundedness of the solution for the discontinuous system is proved first. Then, by using the Kakutani's fixed point theorem of set-valued maps, the existence of a periodic orbit is obtained under some assumptions and constraints. Furthermore, the globally exponentially stable omega$$ \omega $$-periodic orbit is investigated using the Lyapunov functional method. The obtained results can help us better understand the dynamic characteristics of discontinuous delayed systems and have direct applications to the wireless sensor networks for guaranteeing fast response to malicious signals. Finally, the numerical simulations of three examples are given to validate the correctness of the theoretical results.
通讯机构：
[Di Liu; Ximeng Liu] 1;1 School of Mathematics and Statistics, Changsha University of Science and Technology , Changsha 410114, People’s Republic of China
摘要：
In this paper, we consider the long-time behavior of the nonclassical diffusion equation with perturbed parameter and memory on a bounded domain Ω⊂Rn(n≥3) . The main feature of this model is that the equation contains a dissipative term with perturbation parameters −νΔu and the nonlinearity f satisfies the polynomial growth of arbitrary order. By using the nonclassical operator method and a new analytical method (or technique) (Lemma 2.7), the existence and regularity of uniform attractors generated for this equation are proved. Furthermore, we also get the upper semicontinuity of the uniform attractors when the perturbed parameter ν → 0. It is remarkable that if ν = 0, we can get the same conclusion as in the works of Toan et al. [Acta Appl. Math. 170, 789–822 (2020)] and Conti et al. [Commun. Pure Appl. Anal. 19, 2035–2050 (2020)], but the nonlinearity is critical.
