Spatial social networks

We introduce a spatial cost topology in the network formation model analyzed by Jackson and Wolinsky, Journal of Economic Theory (1996), 71: 44–74. This cost topology might represent geographical, social, or individual differences. It describes variable costs of establishing social network connections. Participants form links based on a cost-benefit analysis. We examine the pairwise stable networks within this spatial environment. Incentives vary enough to show a rich pattern of emerging behavior. We also investigate the subgame perfect implementation of pairwise stable and efficient networks. We construct a multistage extensive form game that describes the formation of links in our spatial environment. Finally, we identify the conditions under which the subgame perfect Nash equilibria of these network formation games are stable. We are very grateful for the constructive comments of Matt Jackson and an anonymous referee. We also like to thank Vince Crawford, Marco Slikker, Edward Droste, Hans Haller, Dimitrios Diamantaras, and Sudipta Sarangi for comments on previous drafts of this paper.We acknowledge Jay Hogan for his programming support. Part of this research was done while visiting the CentER for Economic Research, Tilburg University, Tilburg, The Netherlands.Financial support from the Netherlands Organization for Scientific Resrarch (NWO), grant B46-390, is gratefully acknowledged.-->,     

The stability and efficiency of directed communication networks

Abstract. This paper analyzes the formation of directed networks where self-interested individuals choose with whom they communicate. The focus of the paper is on whether the incentives of individuals to add or sever links will lead them to form networks that are efficient from a societal viewpoint. It is shown that for some contexts, to reconcile efficiency with individual incentives, benefits must either be redistributed in ways depending on “outsiders” who do not contribute to the productive value of the network, or in ways that violate equity (i.e., anonymity). It is also shown that there are interesting contexts for which it is possible to ensure that efficient networks are individually stable via (re)distributions that are balanced across components of the network, anonymous, and independent of the connections of non-contributing outsiders.     

Network formation models with costs for establishing links

Abstract. In this paper we study endogenous formation of communication networks in situations where the economic possibilities of groups of players can be described by a cooperative game. We concentrate on the influence that the existence of costs for establishing communication links has on the communication networks that are formed. The starting points in this paper are two game-theoretic models of the formation of communication links that were studied in the literature fairly recently, the extensive-form model by Aumann and Myerson (1988) and the strategic-form model that was studied by Dutta et al. (1998). We follow their analyses as closely as possible and use an extension of the Myerson value to determine the payoffs to the players in communication situations when forming links is not costless. We find that it is possible that as the costs of establishing links increase, more links are formed.     

Tax Competition with Heterogeneous Firms

Abstract

This paper studies tax competition in an economic geography model that allows for agglomeration economies with trade costs and heterogeneous firms. We find that the Nash equilibrium involves a large country charging a higher tax than a small nation. Lower trade costs lead to an intensification of competition, a drop in Nash tax rates and a narrowing of the gap. Since large, productive firms are naturally more sensitive to tax differences in our model, large firms are the crux of tax competition in our model. This also means that tax competition has consequences for the average productivity of big and small nations' industries; by lowering tax rates, a small nation can attract high-productivity firms.     

Good neighbors are hard to find: computational complexity of network formation

We investigate the computational complexity of several decision problems in a simple strategic game of network formation. We find that deciding if a player has a strategy that guarantees him a certain payoff against a given strategy profile of the other players is an NP-complete problem. Deciding if there exists a strategy profile that guarantees a certain aggregate payoff is also NP-complete. Deciding if there is a Nash equilibrium in pure strategies which guarantees a certain payoff to each player is NP-hard. The problem of deciding if a given strategy profile is a Nash equilibrium is investigated as well. We would like to thank both referees for valuable corrections and suggestions and one referee in particular for a very detailed and beneficial critique. We thank Colin de la Higuera for fruitful discussions. Support by the French Ministry for Youth, Education and Research, through project SCSHS-2004-04 is gratefully acknowledged.     

The scheduling and organization of periodic associative computation: Efficient networks

This paper characterizes the efficient decentralized networks for calculating the associative aggregate of cohorts of data of a fixed size that arrive periodically. Radner (1993) proposed this problem of periodic parallel associative computation as a model of the ongoing information processing and communication by the administrative staff of a large organization. For a simpler model in which the organization processes a single cohort of data – which is equivalent to the periodic model when the agents are paid only when busy – he found that the efficient networks are hierarchical but quite irregular, even though the computation problem and technology are each symmetric. In the periodic model in which managers are paid even when idle, it becomes important to minimize idle time when scheduling managers to processing tasks. Such scheduling appears more difficult when each problem is processed by an irregular hierarchy, which suggest that hierarchies might be more regular in the periodic model. However, we show that in a class of efficient networks for periodic computation that spans the efficiency frontier, the processing of each cohort is similar to the efficient processing of a single cohort, and the overall organizational structure is not even hierarchical. Received: 15 October 1994 / Accepted: 6 March 1997     

Optimal mechanisms for siting noxious facilities

We study Bayesian mechanism design in the context of the siting of noxious facilities. Under incomplete information, we characterize optimal mechanisms facilitating the siting and cost sharing of the facility. These mechanisms are allocatively and Pareto efficient. However, it appears that transfers occur when the good is not provided. This result is due to the weakening of the incentive notion to Bayesian–Nash equilibrium and to the balanced budget condition. This phenomenon disappears if the setting is perfectly symmetric.      

Bargaining solutions with non-standard objectives

I examine the pure-strategy solutions of the sealed-bid bargaining game with incomplete information, when the buyer's and seller's objectives are other than the standard objective, namely maximization of expected profit. The motivation for this exploration lies in three problems of the standard formulation: the necessity of assuming common priors, the existence of uncountably many Nash equilibria, with no means for the players to coordinate on any one of them, and the uncertain relationship between these equilibria and observed behavior in bargaining experiments. Specifically, I consider two alternative objectives: minimization of maximum regret, and maximization of maximum profit. The solution concept here is not Nash equilibrium, but rather -individually rational strategy bundle. For that reason, I shall, where appropriate, use the word “solution” in place of “equilibrium.” Yet we find that the notion of Nash Equilibrium reappears, in a sense to be explained. In the minimax-regret case I find (in contrast to the case of expected profit) a unique solution; this solution reduces, for priors with coincident support, to the linear equilibrium of Chatterjee-Samuelson. In the maximum-profit case there are many solutions; they turn out to be slight generalizations of the one-step equilibria of Leininger-Linhart-Radner.     

Hierarchies and information-processing organizations

This paper analyzes organizational structures that minimize information processing costs for a specific organizational task. Organizations consist of agents of limited ability connected in a network. These agents collect and process information, and make decisions. Organizations implement strategies – mappings from environmental circumstances to decisions. The strategies are exogenously given from a class of “pie” problems to be defined in this paper. The notion of efficiency is lexicographic: the primary criterion is minimizing the number of agents, and the secondary criterion is minimizing the number of connections between the agents. In this modeling framework, efficient organizations are not hierarchical for a large number of problems. Hierarchies often fail to exploit fully the information processing capabilities of the agents because in a hierarchy, subordinates have a single superior. Received: 1 December 1995 / Accepted: 11 October 1998     

Endogenous household interaction

Most econometric models of intrahousehold behavior assume that household decision making is efficient, i.e., utility realizations lie on the Pareto frontier. In this paper, we investigate this claim by adding a number of participation constraints to the household allocation problem. Short-run constraints ensure that each spouse obtains a utility level at least equal to what they would realize under (inefficient) Nash equilibrium. Long-run constraints ensure that each spouse obtains a utility level at least equal to what they would realize by cheating on the efficient allocation and receiving Nash equilibrium payoffs in all successive periods. Given household characteristics and the (common) discount factor of the spouses, not all households may be able to attain payoffs on the Pareto frontier. We estimate these models using a Method of Simulated Moments estimator and data from one wave of the Panel Study of Income Dynamics. We find that both short- and long-run constraints are binding for sizable proportions of households in the sample. We conclude that it is important to carefully model the constraint sets household members face when modeling household allocation decisions, and to allow for the possibility that efficient outcomes may not be implementable for some households.     

A Note on Managerial Delegation with Asymmetric and Convex Costs

In this note, we investigate if the standard result by the managerial delegation literature, i.e., the sub‐game perfect Nash equilibrium is not Pareto‐optimal from the firms' viewpoint, still applies when asymmetric and convex costs are introduced into the analysis. In such a framework, the managerial delegation choice still represents a sub‐game Nash perfect equilibrium, but the more efficient firm may obtain higher profits provided that the degree of cost asymmetry between firms is sufficiently large. Copyright © 2015 John Wiley & Sons, Ltd.     

An equilibrium model of insider trading in continuous time

We study a Bayesian–Nash equilibrium model of insider trading in continuous time. The supply of the risky asset is assumed to be stochastic. This supply can be interpreted as noise from nonrational traders (noise traders). A rational informed investor (the insider) has private information on the growth rate of the dividend flow rewarded by the risky asset. She is risk averse and maximizes her inter-temporal utility rate over an infinite time-horizon. The market is cleared by a risk neutral market maker who sets the price of the risky asset competitively as the conditional present value of future dividends, given the information supplied by the dividend history and the cumulative order flow. Due to the presence of noise traders, the market demand does not fully reveal the insider’s private information, which slowly becomes incorporated in prices. An interesting result of the paper is that a nonstandard linear filtering procedure gives an a priori form for the equilibrium strategy to be postulated. We show the existence of a stationary linear equilibrium where the insider acts strategically by taking advantage of the camouflage provided by the noise which affects the market maker’s estimates on private information. In this equilibrium, we find that the insider’s returns on the stock are uncorrelated over long periods of time. Finally, we show that the instantaneous variance of the price under asymmetric information lies between the instantaneous variance of the price under complete and incomplete information. The converse inequalities hold true for the unconditional variance of the price.     

Technology ladders and R&D in dynamic Cournot markets

Motivated by dramatic and unpredictable technological advances in energy production (for instance drilling and extraction of shale oil), we extend Cournot models of competition to incorporate research and development (R&D) that can lead to (stochastic) drops in production costs. Our model combines features of patent racing with dynamic market structure, capturing the interplay between the immediate competition in terms of production rates and the long-term competition in R&D. The resulting Markov Nash equilibrium is found from a sequence of one-step static games arising between R&D successes, and several numerical examples and extensive analysis of the emerging comparative statics are presented. Analyzing the relationship between current market dominance and the level of R&D investments, we find that market leaders tend to invest more, which in some sense makes oligopoly dynamically unstable. We show that anticipated market transitions have long-term impact; for example the potential of future monopoly can spur R&D investment now, even if the firm is presently uncompetitive and not actively producing. We also show that, surprisingly, random innovations have an ambiguous effect on R&D. This feature, which is driven by the Cournot framework, contrasts with the common situation whereby uncertainty lowers innovation and delays R&D investments. Finally, we demonstrate that increased competition may actually increase efforts to innovate through higher desire to achieve dominance. This would match the anecdotal evidence that the threat of market entrants forces incumbents to maintain high R&D.     

The not-so-secret-agent: Professional monitors,hierarchies and implementation

Abstract. It is well-known that, when agents in an organization possess private information that is unverifiable by an outside party, games where agents simply announce their information can have multiple equilibria that may impede the successful implementation of the organization's objectives. We show that the introduction of a professional monitor (e.g. auditor, regulator, supervisor) can help to destroy the “bad' equilibria when agents have private information but have incomplete info rmation about others' information. Received: 21 May 1998 / Accepted: 26 May 2000     

Location decisions and welfare under spatial price discrimination

The welfare effects of regulation are of crucial importance to policy makers. To this end, we present a model of n firms with differentiated costs competing in a linear market within the framework of spatial price discrimination. We prove that the Nash equilibrium locations of firms are always socially optimal irrespective of the number of competitors, the distribution of consumers, firms' cost heterogeneity, the level of privatization, and the number and/or the varieties of the produced goods. We also provide an algorithm on how to find the unique Nash equilibrium in the case of uniformly distributed consumers.     

Sovereign debt: Reputation, seizure and reputation

The interaction between a creditor and a sovereign debtor is described as a ‘one-shot’ game with discrete actions—total or no debt-repudiation and seizure of asset holding abroad. Possible Nash equilibria where each player chooses an action as to maximize his expected payoff given his beliefs about the other player’s action and the implications of those actions on the players’ trustworthy reputation are identified. However, if reputation losses rise convexly with the players’ relative hostility, partial repudiation and seizure can be the preferred strategies. The preferred repudiation and seizure rates are analyzed under asymmetric and symmetric information about the state of the world. (JEL classification F34)     

Taxation in an economy with private provision of public goods

This paper analyses the effects of taxation and subsidies in an economy with private provision of a public good. It is shown that in a situation where all individuals contribute, taxation affects the equilibrium allocation if and only if at least one individual's voluntary contribution to the public good has an impact on the aggregate tax payments of the others. We then consider linear nonneutral tax-subsidy schemes and analyse efficiency and uniqueness of the resulting Nash equilibria. We show that an efficient Nash equilibrium, where all individuals contribute, will in general not be unique, and establish a non-uniformity property which a tax-subsidy scheme must fulfil in order to induce a unique interior equilibrium that is efficient. Throughout the paper it is assumed that individuals fully understand and take into account the government's budget constraint. Received: 3 November 1997 / Accepted: 23 March 1999     

Managerial costs for one-shot decentralized information processing

Radner (1993) proposed a model of decentralized associative computation as a means to understand information processing in organizations. In the model, in which an organization processes a single cohort of data, resources are measured by the number of managers. This paper (i) explains why resources should instead be measured by the time the managers are busy, (ii) shows that, nevertheless, the characterization of sufficient conditions for efficient networks in Radner (1993) and Keren and Levhari (1979) is valid for either measure, (iii) shows that measuring resources by the number of operations leads to sharper results on necessary conditions for efficiency, (iv) strengthens Radner's results on the irregularity of efficient hierarchies, and (v) compares the relative costs of parallelization under the two measures. Received: 28 February 1997 / Accepted: 30 September 1997     

Interlocking directorates in Italy: persistent links in network dynamics

In this work we study the time evolution of interlocking directorates in Italy from 1998 to 2011 by means of dynamical networks. Our purpose is to assess if in Italy there is a connected and stable structure, due to the presence of directors with multiple mandates, like it happens in the German case. We find a very cohesive network structure, due to the presence of a few directors with multiple assignments and, unlike the German case, this structure is stable, but not connected. Moreover we propose an alternative approach to investigate the dynamics, based on temporal networks, in order to quantify the variation of links in a certain time period. We construct a unique cumulative network, where nodes are companies and the existence of an edge is related with the persistence in time of an interlock between two companies. This persistence is due on the one hand to the ownership of a few family firms, and on the other hand to cross-shareholdings between companies. To complete the analysis we also investigate whether the link stability results from the appointments of the same director or from the stepping in/out of different directors.