Farsighted network formation

This paper studies a model of dynamic network formation when individuals are farsighted: players evaluate the desirability of a “current” move in terms of its consequences on the entire discounted stream of payoffs. We define a concept of equilibrium which takes into account farsighted behavior of agents and allows for limited cooperation amongst agents. We show that an equilibrium process of network formation exists. We also show that there are valuation structures in which no equilibrium strategy profile can sustain efficient networks. We then provide sufficient conditions under which the equilibrium process will yield efficient outcomes.     

竞争、不确定性与企业间技术创新合作

新古典经济学认为企业间结网合作与利己短视的理性经济人假设不相一致。对此 ,目前经济理论已有所突破。较早的博弈论无名氏定理指出 ,只要有足够的耐心重复进行博弈就可能达到合作的效果。近来提出的网络形成理论则认为网络的形成及稳定完全依赖于结网的直接间接收益与成本的权衡。但是 ,它们都还不能反映企业所面临的不确定性和市场竞争环境对企业策略行为的影响 ,从而无法解释合作分享为什么会发生在硅谷那样竞争空前激烈、流动异常频繁的地方而在另一些得到政府扶持保护的地方却难现其踪。本文以硅谷为代表的自组织创新网络为研究原型 ,构造了一个基于企业复合实物期权创新合作行为的创新网络模型 ,从中得到了两点新的重要发现 :①与无名氏定理的要求相反 ,体现竞争压力和不确定性的急切感是企业间结网合作的必要条件 ;②能够实现最大增值的创新网络是不断更新的概率暂存网络。     

A Dynamic Model of Network Formation

Network structure plays a significant role in determining the outcome of many important economic relationships; therefore it is crucial to know which network configurations will arise. We analyze the process of network formation in a dynamic framework, where self-interested individuals can form and sever links. We determine which network structures the formation process will converge to. This information allows us to determine whether or not the formation process will converge to an efficient network structure. Journal of Economic Literature Classification Numbers: A14, C7, D20.     

基于专利分析的技术创新网络协同成熟度测度研究

企业进行跨边界网络化合作的目的是利用网络整体效应,实现创新和利益最大化。目前,企业合作过程中面临的关键问题是如何实现组织间协同。通过对技术创新网络协同影响因素及其形成特征进行分析,提出了5种协同状态,并在此基础上构建了技术创新网络协同成熟度评价指标体系,结合OLED产业专利数据进行实证研究。结果表明,该模型能够有效测度技术创新网络协同成熟度,得出全球OLED产业形成的技术创新网络处于协同成熟度模型的管理级,即组织协同阶段。     

Job contact networks

Many workers hear about or obtain their jobs through friends and relatives. The aim of this paper is twofold. First, we relate both individual and aggregate labor market outcomes to the network structure of personal contacts. Second, we study strategic network formation. To this purpose, we develop a model specifying at the individual level both the decision to form contacts with other agents, and the process by which information about jobs is obtained and transmitted. We show that equilibrium networks always exist and that only moderate levels of network asymmetry can be sustained at equilibrium. Also, we establish a general non-monotonicity result on information flow and unemployment with respect to network size in symmetric networks.     

Network formation and stable equilibrium

We study the non-cooperative formation of a (directed) network that builds upon one-way immediate links. Our novel feature is that we require circular paths of links for productive activities. This captures more clearly the higher level of coordination that is often required for network formations than models such as those of Jackson and Wolinsky [A strategic model of social and economic networks, J. Econ. Theory 71 (1996) 44-74] and Bala and Goyal [A non-cooperative model of network formation, Econometrica 68 (2000) 1181-1229], in that in our model a single agent's unilateral action is limited in affecting the network structure. We completely characterize the class of Nash equilibria by showing that the minimality of a graph is both necessary and sufficient (Theorem 1). We also propose the concept of a stable network that is similar to the pairwise stability of Jackson and Wolinsky (1996). We show that stable equilibria are a wheel, a trivial network, or a sub-wheel partitioned network (Theorem 2). We modify the Bala and Goyal (2000) dynamic process with inertia, and obtain the convergence to stable equilibria regardless of the initial state (Theorem 3).     

区域产业集群形成与发展的GERT网络研究

运用随机网络理论,构建了区域产业集群形成与发展的GERT网络模型,提出了区域产业集群形成与发展的“夭折”概率与“成熟”概率两个概念,并以高科技产业集群为例求解。在此基础上,研究政府在产业集群的不同阶段给予支持时,各种方案对产业集群形成与发展的作用效果。产业集群“成熟”概率的变化,说明了政府在产业集群发展的初期给予支持是最优的选择,进而说明了政府对产业集群支持的必要性以及支持方案的选择效果。     

基于知识权力和知识交互行为的产业集群多重知识网络演化分析

针对产业集群知识网络中客观存在但却未受关注的知识权力,结合自适应知识交互行为,采用多主体建模与仿真方法,分析知识权力的动态变化导致的产业集群多重知识网络演化。结果表明:知识权力差距及知识交互行为是促使产业集群多重知识网络形成及演化的基础,产业集群多重知识网络的演化过程具有典型的阶段性特征,其网络结构呈现出网络节点密集性与稀疏性相结合、强联结与弱联结并存、度分布高度异质性的特征。利用实际产业集群网络验证仿真结果,证明了该仿真模型的可信性。     

A network experiment in continuous time: The influence of link costs

In recent work on non-cooperative network formation star-shaped networks play an important role. In a particular theoretical model of Bala and Goyal (2000) center-sponsored stars are the only strict Nash networks. In testing this theoretical model, Falk and Kosfeld (2003) do not find experimental evidence that players select the center-sponsored star. Based on a slight modification of Bala and Goyal’s model, we design a network formation experiment in which, depending on link costs, periphery-sponsored stars and the empty network are the only strict Nash networks. We observe that almost all groups not only reach a strict Nash network once but also switch the center player in periphery-sponsored stars several times. The main innovation in our experiment is to use a continuous time framework which we believe to be a more realistic setting to study behavior in network formation situations and which makes coordination on stars much easier than simultaneous strategy adaptation in discrete time. Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s10683-006-9125-1. JEL Classification C72 · C92 · D81     

风险投资退出股权关联价值拍卖模型及仿真研究——基于Deffuant模型的群体局部博弈及社会网络演化

首先模拟了风险投资退出市场中社会网络的形成机理和演化过程,刻画了外部投资者的私人信息在该社会网络中的传递和交互;然后考虑存在群体局部交互博弈时外部投资者对股权的评价及报价策略的动态演进;最后建立了包含社会网络演化及网络群体局部动态博弈的股权关联价值拍卖模型,并进行了仿真分析。     

Farsighted strategies in the formation of a communication network

I examine the formation of a specific communication network, a variant of the two-way flow model, in which agents have farsighted strategies. I show that the likelihood to form efficient networks tends to zero for sufficiently large network sizes.     

Proximity, knowledge integration and innovation: an agenda for agent-based studies

In this paper, we develop a theoretical model able to capture some of the main features that govern knowledge sharing and innovation. We pursue our target developing an agent-based model in which the social network of interactions is specified as a knowledge resource, and knowledge integration is seen as the process by which the resource can be applied to innovation. The results of the simulation exercises show that the initial architecture of acquaintance networks is a crucial factor for innovation. Innovating has proven to be more than simply equating endowments of initial skills with firm performance. In fact, the performance of the system showed high sensitivity to the arrangement of the firm’s initial location in the social network. Moreover, the way in which acquaintance networks were mobilized emerged as a key determinant of innovation patterns. The model presented here is a relatively theoretical, stylized model and we employ it to draw some general, albeit preliminary conclusions, while illustrating some of the theory relevant to the issues discussed. It is argued that the model might serve the purpose of setting an agenda for further research along this line of investigation—that is, knowledge integration patterns and firms partnerships formation.     

STRUCTURAL HOMOPHILY

Homophily, or the fact that similar individuals tend to interact with each other, is a prominent feature of economic and social networks. I show that the equilibrium structure of homophily has empirical power. I build a strategic model of network formation, which produces a unique equilibrium network. Individuals have homophilic preferences and face capacity constraints on the number of links. I develop a novel empirical method, based on the shape of the equilibrium network, which allows for the identification and estimation of the underlying homophilic preferences. I apply this new methodology to the formation of friendship networks.     

面向“一带一路”的企业技术标准联盟合作意愿研究——基于领导—追随者网络一致性模型

基于领导—追随者网络一致性模型,分析联盟规模、结构和领导者位置等因素对“一带一路”企业技术标准联盟成员合作意愿的影响。研究发现：(1)本土制造网络情景下中国企业领导联盟合作意愿更强,而本土供应商为领导者联盟的合作意愿较弱;(2)委托代理网络情景下“一带一路”沿线主体领导联盟的合作意愿较弱;(3)产业链网络情景下靠近产业链中部的主体领导联盟合作意愿更强;(4)对于互联互通网络而言,无论哪个企业为领导者,合作意愿都相同;(5)抱团出海网络情景下中国企业领导联盟合作意愿最强。研究结论有助于进一步探究联盟网络特征与联盟合作意愿间的关系,为面向“一带一路”企业技术标准联盟提供新分析框架,对于中国企业发挥“一带一路”技术标准联盟网络合作引导者作用和联盟治理实践具有一定启示意义。     

Morphogenesis Of Social Networks And Coexistence Of Technologies ∗

The aim of the article is to relate the formation of influence networks to the coexistence of technologies in the long run. In the spirit of Plouraboue et al. (1998), we postulate that potential adopters of a technology are situated in a social network. In our model, initial relations are partly negative and all the expected utilities are revised in parallel. In the case of an exogenous network, opinions can fluctuate endlessly. When agents reallocate their relationships, this reinforces trust in agents whose opinion is close to theirs. As a result of this process, the network stabilizes in the long run, generating diversity in expected utilities.     

平台内网络效应与跨平台网络效应作用机制研究

网络效应作为商务平台发展过程中重要研究对象,其实现是潮流效应（Bandwagon Effect）、规模效应（Scale Effect）、羊群效应（Herding Effect）、市场中介效应（Market-mediated Effect）和锁定效应（Lock-in Effect）综合作用的结果。随着大众生产（Peer Production）、大规模协作（Mass Collaboration）、共享经济（Shared Economy）等新生产方式的产生,平台为更好地发挥新时期用户的“产销者”作用,提升平台综合竞争力,开始构建平台组合以形成跨平台网络效应。基于对国内外学者的文献梳理,拓展了网络效应研究的一般思路,从新经济环境下的多平台竞争模式出发,探究平台内网络效应和跨平台网络效应的形成途径和作用机制,挖掘跨平台网络效应的主要表现形式,具体包括“新平台+旧平台”模式、“平台+在线论坛”模式和“平台+开源社区”模式。最后指明未来互联网商务平台网络效应的研究方向,以期为国内外从事网络效应研究的学者提供借鉴。     

多维邻近视角下长江经济带区域金融空间联系特征及其影响机制

研究运用引力模型、网络分析、聚类分析、空间自相关分析和经济重心模型等方法剖析了长江经济带区域金融空间联系网络特征以及联系总量格局,并在多维邻近视角下采用空间杜宾模型探究了区域金融能力与金融网络规模的影响机制,研究发现:①"多核心"的金融空间联系网络格局较为稳定,网络复杂度持续升级,呈现"东密西疏"的空间分布特征,且在空间上形成三大层级性明显的金融辐射圈;②金融空间联系格局展现出"核心-边缘"的发展形态,空间集聚特征明显,发展重心在演进过程中呈现反"Z"形变化特征;③金融空间联系能通过信息技术发展打破传统地理空间距离壁垒,具有明显的多维邻近效应,其中城市经济规模、工业基础能力、产业升级导向和城市创新能力是区域金融能力与金融网络格局形成的主要影响因素,而政府供给导向因素具有较强的空间溢出效应,区域间的政府竞合行为有利于金融要素的流转与联系。     

Networks of Free Trade Agreements among Heterogeneous Countries

The paper examines the formation of free trade agreements as a network formation game. We consider an n‐country model in which international trade occurs between economies with imperfectly competitive product markets. In each country, the labor market is either unionized or non‐unionized. We show that, if all countries are non‐unionized, the global free trade network is both the unique pairwise stable network and the unique efficient network. If all countries are unionized, the global free trade network is pairwise stable and the unique efficient network among the class of symmetric networks. If some countries are unionized while others are non‐unionized, other networks apart from the global free trade network may be pairwise stable. However, the efficient network is still the global free trade network. Thus, a conflict between stability and efficiency may occur. Moreover, starting from the network in which no country has signed a free trade agreement, all sequences of networks due to continuously profitable deviations do not lead (in most cases) to the global free trade network, even when global free trade is stable.     

Network formation and social coordination

This paper develops a simple model to examine the interaction between partner choice and individual behavior in games of coordination. An important ingredient of our approach is the way we model partner choice: we suppose that a player can establish ties with other players by unilaterally investing in costly pairwise links. In this context, individual efforts to balance the costs and benefits of links are shown to lead to a unique equilibrium interaction architecture. The dynamics of network formation, however, has powerful effects on individual behavior: if costs of forming links are below a certain threshold then players coordinate on the risk-dominant action, while if costs are above this threshold then they coordinate on the efficient action. These findings are robust to modifications in the link formation process, different specifications of link formation costs, alternative models of mutations as well as the possibility of interaction among indirectly connected players.     

Coordination in evolving networks with endogenous decay

This paper studies an evolutionary model of network formation with endogenous decay, in which agents benefit both from direct and indirect connections. In addition to forming (costly) links, agents choose actions for a coordination game that determines the level of decay of each link. We address the issues of coordination (long-run equilibrium selection) and network formation by means of stochastic stability techniques. We find that the long-run behavior of the system depends on a fine interplay of the link cost and the trade-off between efficiency and risk-dominance.