Chaotic dynamics in three dimensions: A topological proof for a triopoly game model

We rigorously prove the existence of chaotic dynamics for a triopoly game model. In the model considered, the three firms are heterogeneous and in fact each of them adopts a different decisional mechanism, i.e., linear approximation, best response and gradient mechanisms, respectively. The method we employ is the so-called “Stretching Along the Paths” (SAP) technique, based on the Poincaré–Miranda Theorem and on the properties of the cutting surfaces.     

Study on a 3-dimensional game model with delayed bounded rationality

A nonlinear dynamic triopoly game model is studied based on the theory of nonlinear dynamics and previous researches in this paper. A lagged structure is introduced to the model to study stability conditions of the Nash equilibrium under a local adjustment process when players price their products with delayed bounded rationality. Numerical simulations are provided to demonstrate the complexity of system evolvement and influence of the strategy of delayed bounded rationality on system stability. We find that besides the lagged structure, suitable delayed parameters are also important factors to eliminate chaos or expand the stable region of the system, and various players’ adjustment parameters have different effect on stability of the system.     

When “Better” is better than “Best”

We consider two-player normal form games where each player has the same finite strategy set. The payoffs of each player are assumed to be i.i.d. random variables with a continuous distribution. We show that, with high probability, the better-response dynamics converges to pure Nash equilibrium whenever there is one, whereas best-response dynamics fails to converge, as it is trapped.     

带有环境反馈的不对称劳动分工博弈模型

带有环境反馈的两策略博弈被广泛研究,本文研究带有环境反馈的三策略博弈模型.环境被分为富裕斑块和贫穷斑块,富裕的斑块可以为玩家提供额外的环境收益,而贫穷斑块不为玩家提供任何收益.首先,建立模仿者动力学模型,推导模型平衡点稳定性的充分条件.该模型平衡点的稳定性取决于各策略的成本、富裕环境的收益、策略C对策略A和策略B的干扰以及策略A和策略B的合作效益.此外,通过对模型进行数值模拟,可以发现与初始期望结果一致,并且得到了在异质环境下各策略的频率.     

Static and dynamic best-response potential functions for the non-linear Cournot game

We show that the Cournot oligopoly game with non-linear market demand can be reformulated as a best-response potential game where the best-response potential function is linear-quadratic in the special case where marginal cost is normalized to zero. We also propose a new approach to show that the open-loop differential game with Ramsey dynamics admits a best-response Hamiltonian potential corresponding to the sum of the best-response potential function of the static game plus the scalar product of transition functions multiplied by the fictitious costate variables. Unlike the original differential game, its best-response representation yields the map of the instantaneous best reply functions.     

Hopf bifurcation and stability crossing curves in a cobweb model with heterogeneous producers and time delays

We study a continuous time cobweb model with discrete time delays where heterogeneous producers behave as adapters in the market. Specifically, they partially adjust production (which is subject to some gestation lags) towards the profit-maximising quantity under static expectations. The dynamics of the economy is described by a two-dimensional system of delay differential equations. We characterise stability properties of the stationary state of the system and show the emergence of Hopf bifurcations. We also apply some recent mathematical techniques (stability crossing curves) to show how heterogeneous time delays affect the stability of the economy.     

Fashion cycle dynamics induced by agents' heterogeneity for generic bell-shaped attractiveness functions

ABSTRACT

We extend the exchange economy evolutionary discrete-time model with heterogeneous agents introduced in ‘Fashion cycle dynamics in a model with endogenous discrete evolution of heterogeneous preferences’, by A. Naimzada and M. Pireddu, appeared in Chaos: An Interdisciplinary Journal of Nonlinear Science 28, 055907 (2018), by considering generic bell-shaped attractiveness functions for the two groups of agents, increasing for low visibility levels, but decreasing when the visibility of the group exceeds a given threshold value, due to a congestion effect. The reproduction level of a group is related to its attractiveness degree, which depends on its social visibility level, determined by the consumption choices of the agents in that group. We investigate the asymptotic heterogeneity among agents, finding that the global dynamics may differ according to the chosen functional form for the attractiveness. Nonetheless, the model is still able to reproduce the recurrent dynamic behaviour typical of the fashion cycle.     

The design of a Tort law to control accidents

In this paper we analyse a two-stage game involving the government and n agents who engage in a single activity (driving). The government establishes the legal policy setting and the agents proceed to play a non-cooperative game of incomplete information with a risk of accident in which their behavioral strategy is their level of care. We examine the Nash-equilibrium conditions for single-activity accidents between heterogeneous agents, ‘good’ drivers or ‘bad’ drivers allowing a variable damage function and a liability rule defined on the cube. The relative desirability for society of alternative equilibria and the conditions under which they can obtain are discussed. The constraints which circumscribe the ability of the government to induce an equilibrium involving careful driving are demonstrated. It transpires that when the proportion of good drivers increases, it becomes more difficult to sustain a careful equilibrium whereas an equilibrium of reckless behavior becomes easier to sustain. Various extensions of the models are also presented.     

Hopf bifurcations in dynamical systems

The onset of instability in autonomous dynamical systems (ADS) of ordinary differential equations is investigated. Binary, ternary and quaternary ADS are taken into account. The stability frontier of the spectrum is analyzed. Conditions necessary and sufficient for the occurring of Hopf, Hopf–Steady, Double-Hopf and unsteady aperiodic bifurcations—in closed form—and conditions guaranteeing the absence of unsteady bifurcations via symmetrizability, are obtained. The continuous triopoly Cournot game of mathematical economy is taken into account and it is shown that the ternary ADS governing the Nash equilibrium stability, is symmetrizable. The onset of Hopf bifurcations in rotatory thermal hydrodynamics is studied and the Hopf bifurcation number (threshold that the Taylor number crosses at the onset of Hopf bifurcations) is obtained.

     

Existence of the core in a heterogeneous divisible commodity exchange economy

We consider the exchange of a heterogeneous divisible commodity modeled as a measurable space. Under rational, continuous and convex preferences over characteristic measures a weak core is shown to exist. Further, a core exists if characteristic measures are mutually absolutely continuous. Applied to the land trading economy, the core existence results in Berliant (J Math Econ 14:53–56, 1985) and Dunz (Reg Sci Urban Econ 21:73–88, 1991) are obtained.     

异质预期条件下房价波动非线性延滞差分方程

通过建立蛛网模型分析经济变动对具有后向预期性质的房地产市场的价格波动的影响.其中,市场需求函数采用简单使用者成本模型,而供给函数则以存量-流量模型为基础.通过建立一组n阶延滞差分方程来分析一类异质后向预期房价波动模型的性质,例如均衡或振荡,收敛或偏离等.结果显示需求弹性小于供给弹性并不是形成振荡的必要条件.房价的波动会随着异质后向预期假设以及其他内生因素的不同而产生本质不同的变化.     

基于模糊加值信息的供应链协调均衡研究

研究由一个供应商和两个零售商组成的供应链共享信息均衡问题。两个零售商具有不同的私有成本信息。当零售商不公开此成本信息时,其他的零售商和供应商只能推断出该信息的模糊分布。不同市场需求参数下,使零售商和供应商均达到最大利润的局势也有所不同。为了使供应链上的供应商和零售商达到双赢,分析了各同均衡策略存在的前提条件。     

On the relationship between uniqueness and stability in sum-aggregative,symmetric and general differentiable games

This article explores the relationship between uniqueness and stability in differentiable regular games, with a major focus on the important classes of sum-aggregative, two-player and symmetric games. We consider three types of popular dynamics, continuous-time gradient dynamics as well as continuous- and discrete-time best-reply dynamics, and include aggregate-taking behavior as a non-strategic behavioral variant. We show that while in general games stability conditions are only sufficient for uniqueness, they are likely to be necessary as well in models with sum-aggregative or symmetric payoff functions. In particular, a unique equilibrium always verifies the stability conditions of all dynamics if strategies are equilibrium complements, and this also holds for both continuous-time dynamics if strategies are equilibrium substitutes with bounded slopes. These findings extend to the case of aggregate-taking equilibria. We further analyze the stability relations between the various dynamics, and demonstrate that the restrictive nature of the discrete dynamics originates from simultaneity of adjustments. Asynchronous decisions or heterogeneous forward thinking may stabilize the adjustment process.     

Equilibrium existence and uniqueness in network games with additive preferences

A directed network game of imperfect strategic substitutes with heterogeneous players is analyzed. We consider concave additive separable utility functions that encompass the quasi-linear ones. It is found that pure strategy Nash equilibria verify a non-linear complementarity problem. By requiring appropriate concavity in the utility functions, the existence of an equilibrium point is shown and equilibrium uniqueness is established with a P-matrix. For this reason, it appears that previous findings on network structure and sparsity hold for many more games.     

Dynamics and steady-state analysis of a consumer-resource model

This paper is concerned with the dynamics of a consumer-resource reaction diffusion model in the heterogeneous environment, proposed by Zhang et al. (2017). We use the comparison principle to improve the ultimate bounds step by step, and show that the unique steady state is globally asymptotically stable if the resources are fully limited uniformly in space and consumer population abundance is homogeneous in space.     

Analysis of epidemic spreading of an SIRS model in complex heterogeneous networks

In this paper, we study the spreading of infections in complex heterogeneous networks based on an SIRS epidemic model with birth and death rates. We find that the dynamics of the network-based SIRS model is completely determined by a threshold value. If the value is less than or equal to one, then the disease-free equilibrium is globally attractive and the disease dies out. Otherwise, the disease-free equilibrium becomes unstable and in the meantime there exists uniquely an endemic equilibrium which is globally asymptotically stable. A series of numerical experiments are given to illustrate the theoretical results. We also consider the SIRS model in the clustered scale-free networks to examine the effect of network community structure on the epidemic dynamics.     

The social diversification of fashion

We propose a model to investigate the dynamics of fashion traits purely driven by social interactions. We assume that people adapt their style to maximize social success, and we describe the interaction as a repeated group game in which the payoffs reflect the social norms dictated by fashion. On one hand, the tendency to imitate the trendy stereotypes opposed to the tendency to diverge from them to proclaim identity; on the other hand, the exploitation of sex appeal for dating success opposed to the moral principles of the society. These opposing forces promote diversity in fashion traits, as predicted by the modeling framework of adaptive dynamics. Our results link the so-called horizontal dynamics—the primary driver of fashion evolution, compared with the vertical dynamics accounting for interclass and economic drivers—to style variety.     

内生网络环境下具有异质连接费用的局部策略互动

考察内生网络环境下局中人之间的局部策略互动, 网络中的局中人只与直接邻居进行协同对策. 网络生成的过程中, 建立连接的费用是异质的~(具有两种水平), 与采取有效行动的局中人建立连接时执行高水平费用, 与采取风险占优行动的局中人建立连接时执行低水平费用. 在异质连接费用的情形下, 首次较为完整地给出了均衡网络的结构特性和局中人的行动选择, 并分析了费用参数对均衡结果的影响.     

The distribution of wealth and the effect of extortion in structured populations

Despite that the heterogeneous distribution of wealth is widely observed in social, economical and biological system, few studies have been conducted to explore its influence on the evolutionary dynamics in populations. This paper discusses this problem by introducing a heterogeneous wealth allocation mechanism controlled by a tunable parameterα . Our study shows that there is a positive relationship between the level of cooperation and the extent of heterogeneity of wealth distribution. More importantly, we show that the catalytic effect of extortioners can be significantly strengthened if wealth is heterogeneously distributed among the whole population. Cooperators and extortioners can co-exist if the value of αis moderate. We explain this phenomenon by arguing that this heterogeneous allocation mechanism enables three types of strategists to form clusters around several rich cooperating neighbors initially. Clusters of defectors tend to be eliminated at early stages of evolution.     

Dynamics of a delayed Lotka–Volterra competition model with directed dispersal

We consider a diffusive Lotka–Volterra competition system with stage structure, where the intrinsic growth rates and the carrying capacities of the species are assumed spatially heterogeneous. Here, we also assume each of the competing populations chooses its dispersal strategy as the tendency to have a distribution proportional to a certain positive prescribed function. We give the effects of dispersal strategy, delay, the intrinsic growth rates and the competition parameters on the global dynamics of the delayed reaction diffusion model. Our result shows that competitive exclusion occurs when one of the diffusion strategies is proportional to the carrying capacity, while the other is not; while both populations can coexist if the competition favors the latter species. Finally, we point out that the method is also applied to the global dynamics of other kinds of delayed competition models.