Fair allocation in networks with externalities

I prove existence and uniqueness of a component efficient and fair allocation rule when the value of the network is allowed to exhibit any type of externalities across its components. This is done by means of a new specification of the value function, generalizing partial results appearing in Myerson [Myerson, R.B., 1977a. Graphs and cooperation in games. Math. Operations Res. 2, 225–229], Feldman [Feldman, B.E., 1996. Bargaining, coalition formation and value. PhD dissertation. State University of New York at Stony Brook] and Jackson and Wolinsky [Jackson, M.O., Wolinsky, A., 1996. A strategic model of social and economic networks. J. Econ. Theory 71, 44–74]. This component efficient and fair allocation rule is found closely related to an extension of the Shapley value to TU-games in partition function form proposed by Myerson [Myerson, R.B., 1977b. Values of games in partition function form. Int. J. Game Theory 6 (1), 23–31].     

On the formation of interaction networks in social coordination games

There are many situations where two interacting individuals can benefit from coordinating their actions. We examine the endogenous choice of partners in such social coordination games and the implications for resulting play. We model the interaction pattern as a network where individuals periodically have the discretion to add or sever links to other players. With such endogenous interaction patterns we see multiple stochastically stable states of play, including some that involve play of equilibria in the coordination game that are neither efficient nor risk-dominant. Thus the endogenous network structure not only has implications for the interaction pattern that emerges, but it also has a significant impact on the play in the coordination game relative to what would arise if the same interaction network were exogenous.     

Farsightedly stable networks

A set of networks G is pairwise farsightedly stable (i) if all possible farsighted pairwise deviations from any network g G to a network outside G are deterred by the threat of ending worse off or equally well off, (ii) if there exists a farsighted improving path from any network outside the set leading to some network in the set, and (iii) if there is no proper subset of G satisfying conditions (i) and (ii). A non-empty pairwise farsightedly stable set always exists. We provide a full characterization of unique pairwise farsightedly stable sets of networks. Contrary to other pairwise concepts, pairwise farsighted stability yields a Pareto dominant network, if it exists, as the unique outcome. Finally, we study the relationship between pairwise farsighted stability and other concepts such as the largest pairwise consistent set and the von Neumann–Morgenstern pairwise farsightedly stable set.     

Trading networks with price-setting agents

In a wide range of markets, individual buyers and sellers trade through intermediaries, who determine prices via strategic considerations. Typically, not all buyers and sellers have access to the same intermediaries, and they trade at correspondingly different prices that reflect their relative amounts of power in the market. We model this phenomenon using a game in which buyers, sellers, and traders engage in trade on a graph that represents the access each buyer and seller has to the traders. We show that the resulting game always has a subgame perfect Nash equilibrium, and that all equilibria lead to an efficient allocation of goods. Finally, we analyze trader profits in terms of the graph structure — roughly, a trader can command a positive profit if and only if it has an “essential” connection in the network, thus providing a graph-theoretic basis for quantifying the amount of competition among traders.     

Evolution of networks—an experimental analysis

It is the main aim of our paper to study network formation in experimental setups in discrete and continuous time. Our design is inspired by the theoretical model on network formation by Bala and Goyal (Econometrica, 68(5): 1181–1229, 2000) as well as the experiments by Callander and Plott (J. Public Econ., 89: 1469–1495, 2005) and Falk and Kosfeld (IEW Working Paper, University of Zürich, Zürich, Switzerland, No. 146, 2003). In particular, we analyze the role of star-shaped networks which are strict Nash-equilibria of the corresponding network formation game. Our experimental results show that strict Nash networks prove to be a good indicator for predicting network formation, particularly in continuous time. In explaining our results, it turns out that, among others, the complexity in coordinating on stars, the inequity aversion against unequal payoff distribution in the network, and the groups’ degrees of activity are the most important determinants for the formation of strict Nash networks.      

One-way flow networks: the role of heterogeneity

I study a one-way flow connections model in which players are heterogeneous with respect to values and the costs of establishing a link. I show that values and costs heterogeneity are equally important in determining the level of connectedness and the architecture of equilibrium networks. I also show that when asymmetries are independent of the potential partner there are distributions of costs and values for which centrality is a distincitive feature of equilibrium networks. This sharply contrasts with the homogeneous case.I thank an anonymous referee for useful comments. The paper has benefited from discussion with Gabriella Conti, Jose Luis Moraga-Gonzalez, Fernando Vega-Redondo and Sanjeev Goyal.     

Existence of Nash networks in one-way flow models

This paper addresses the existence of Nash equilibria in one-way flow models in a number of different settings. In these models players form costly links with other players and obtain resources from them through the directed path connecting them. We find that heterogeneity in the costs of establishing links plays a crucial role for the existence of Nash networks. The paper also provides conditions for the existence of Nash networks in models where costs and values of links are heterogeneous. We would like to thank an anonymous referee for useful suggestions. We would also like to thank Hans Haller and participants at the AEA Meetings 2007 for helpful comments. Sudipta Sarangi acknowledges the support of NSF grant HSD-0527315 and the hospitality of CREUSET, Jean Monnet University.     

Coalition formation in general apex games under monotonic power indices

An apex game consists of one apex player and a set of minor players. We identify two key properties of apex games and use them to introduce the class of general apex games. We derive players' preferences over winning coalitions by applying strongly monotonic power indices on such a game and all its subgames and investigate whether there are core stable coalitions in the induced hedonic coalition formation game. Besides several general results, in particular, we develop conditions on the game for the Shapley–Shubik index, the Banzhaf index, and the normalized Banzhaf index.     

核心企业网络能力、创新网络与科创型特色小镇发展——以杭州云栖小镇为例

科创型特色小镇作为我国推行创新驱动发展战略的重要部署,对当地创新创业发挥着重要作用。拥有核心企业主导的创新网络的科创型特色小镇,具有更强的发展动力。因此,探索核心企业网络能力、创新网络与科创型特色小镇发展之间的关系具有重大意义。运用案例研究方法,以杭州云栖小镇为例展开研究,结果发现：①创新网络演化阶段可以划分为差距清晰化阶段、提升探索阶段和成熟规范化阶段;②核心企业网络能力对创新网络演化发展具有促进作用,并且在创新网络演化不同阶段存在差异性;③核心企业网络能力、创新网络和科创型特色小镇产业发展存在协同演化。     

Networks and farsighted stability

We provide a new framework for the analysis of network formation and demonstrate the existence of farsightedly consistent directed networks. Our framework extends the standard notion of a network and also introduces the notion of a supernetwork. A supernetwork is made up of a collection of directed networks (the nodes) and represents (via the arcs connecting the nodes) preferences and rules governing network formation. By extending Chwe's 1994 result on the nonemptiness of farsightedly consistent sets, we show that for any supernetwork there exists a nonempty subset of farsightedly consistent directed networks.     

中小企业技术创新网络的知识创造研究

中小企业以知识创造为目标构建或加入技术创新网络,以与网络中其它组织之间的优势互补、相互协作的方式来进行合作创新,为中小企业技术创新能力的提高提供了可行性思路。将典型的技术创新网络分为弱连接和强连接两种形态,在分析网络特征及知识创造过程的基础上,分别提出了两种形态在技术创新网络内部知识创造的机制模型。     

Globally evolutionarily stable portfolio rules

The paper examines a dynamic model of a financial market with endogenous asset prices determined by short-run equilibrium of supply and demand. Assets pay dividends that are partially consumed and partially reinvested. The traders use fixed-mix investment strategies (portfolio rules), distributing their wealth between assets in fixed proportions. Our main goal is to identify globally evolutionarily stable strategies, allowing an investor to “survive,” i.e., to accumulate in the long run a positive share of market wealth, regardless of the initial state of the market. It is shown that there is a unique portfolio rule with this property—an analogue of the famous Kelly rule of “betting your beliefs.” A game theoretic interpretation of this result is given.     

Voting in small networks with cross-pressure

We present a model of participation in elections in small networks, in which citizens suffer from cross-pressures if voting against the alternative preferred by some of their social contacts. We analyze how the existence of cross-pressures may shape voting decisions, and so, political outcomes; and how parties may exploit this effect to their interest. We characterize the strong perfect equilibria of the game and show that, in equilibrium, the social network determines which party wins the election. We also show that to dispose of the citizens better connected in the network with the other faction is not a guarantee to win the election.      

Information-sharing in social networks

We present a new model for reasoning about the way information is shared among friends in a social network and the resulting ways in which the social network fragments. Our model formalizes the intuition that revealing personal information in social settings involves a trade-off between the benefits of sharing information with friends, and the risks that additional gossiping will propagate it to someone with whom one is not on friendly terms but who is within oneʼs community. We study the behavior of rational agents in such a situation, and we characterize the existence and computability of stable information-sharing configurations, in which agents do not have an incentive to change the set of partners with whom they share information. We analyze the implications of these stable configurations for social welfare and the resulting fragmentation of the social network.     

Pillage and property

This paper introduces a class of coalitional games, called pillage games, as a model of Hobbesian anarchy. Any coalition can pillage, costlessly and with certainty, any less powerful coalition. Power is endogenous, so a pillage game does not have a characteristic function, but pillage provides a domination concept that defines a stable set, which represents an endogenous balance of power. Every stable set contains only finitely many allocations, and can be represented as a farsighted core. Additional results are obtained for particular games, including the game in which the power of each coalition is determined by its total wealth.     

Principles for the design of management control systems in knowledge networks: Experiences involving the European technology networks

The aim of this paper is to analyse technology-knowledge networks, especially the aspects relating to management control. The management of technology knowledge in a network is characterised by a number of special features that are typical of this form of organization, on the basis of which, we point out the main obstacles and disadvantages that condition the achievement of efficiency of their management. We will analyse management in these networks in light of the experience of various European institutions that actively participate in networks for the development of technological projects. The principal mechanisms used for the control of management will be obtained from the empirical study. Finally, on the basis of the empirical verification, we will consider the development of certain general principles for control in order to achieve greater efficiency in the management of knowledge in these networks.     

Bayesian learning in social networks

We extend the standard model of social learning in two ways. First, we introduce a social network and assume that agents can only observe the actions of agents to whom they are connected by this network. Secondly, we allow agents to choose a different action at each date. If the network satisfies a connectedness assumption, the initial diversity resulting from diverse private information is eventually replaced by uniformity of actions, though not necessarily of beliefs, in finite time with probability one. We look at particular networks to illustrate the impact of network architecture on speed of convergence and the optimality of absorbing states. Convergence is remarkably rapid, so that asymptotic results are a good approximation even in the medium run.     

Competition in telecommunication networks with call externalities

This paper describes a model involving two interconnected networks offering different degrees of quality. In these networks, there are call externalities enabling consumers to assess the quality of the calls they send and receive. Networks compete in two-part tariffs. Our aim is to show that the “profit neutrality” result no longer applies due to network asymmetry and call externalities. In the case of non reciprocal access charges, call externalities generate private incentives enabling each competitor to charge low access prices. This reduces the risk of tacit collusion as competitors are free to negotiate their access charges.      

基于多层网络视角的核心企业成长位移研究

伴随集群核心企业在其成长发展过程中发生的迁移行为,企业赖以获取重要资源的主要渠道将随之发生网络地理位置的转移。基于企业外部网络成长环境的分层性特点来探讨这种位置转移的不同方式及其影响结果。在首先界定核心企业成长空间三层网络的基础上,探讨了集群核心企业在其成长过程中在三层网络内位置迁移的不同方式,分析了不同位移方式下三层网络上网络资源分布的变化及对企业竞争力提升可能产生的影响,初步构建了核心企业在三层网络内成长位移与竞争力提升相关性研究的二维理论模型。     

技术创新网络核心企业领导力影响因素研究

技术创新网络中核心企业的地位及作用一直是学者们关注的热点问题。近年来,核心企业领导力的概念逐渐引起人们的重视。在梳理技术创新网络、领导力、核心企业及核心企业领导力等相关理论研究成果的基础上,对技术创新网络核心企业领导力的内涵进行了进一步剖析和界定,运用理论探索和问卷调研方法,分析了核心企业领导力影响因素,建立了核心企业领导力影响因素概念模型,并进行了实证研究。结果表明：知识资源、网络能力、网络结构和领导者特质是影响技术创新网络核心企业领导力的主要因素。