A core equivalence theorem with an arbitrary communication structure

We formalize the concept of a communication structure by identifying it with a partition of the set of agents. Thus, a coalition can form if and only if it belongs to the given partition. Within this framework we are able to show that for every integer J≧2, if we put the uniform distribution on the space of partitions that contain exactly (or, no more than) J coalitions, the probability that such a partition will contain a blocking coalition for any Pareto optimal allocation which is bounded away from being competitive, is arbitrarily close to 1, as the number of individuals increases.     

Random aggregation without the Pareto principle

Barberà-Sonnenschein (J Econ Theory 18:244–254, 1978) have shown that any binary and Paretian random social choice function can be associated with a mapping which associates a real number with each coalition of individuals. This function gives, for each coalition, the power that this group has in imposing on society, their common preference relation on a pair of alternatives. The aim of this paper is to extend this result, showing that the Pareto criterion is not a necessary condition for the existence of such a coalitional power function.     

Transversals, systems of distinct representatives, mechanism design, and matching

A transversal generated by a system of distinct representatives (SDR) for a collection of sets consists of an element from each set (its representative) such that the representative uniquely identifies the set it belongs to. Theorem 1 gives a necessary and sufficient condition that an arbitrary collection, finite or infinite, of sets, finite or infinite, have an SDR. The proof is direct, short. A Corollary to Theorem 1 shows explicitly the application to matching problems. In the context of designing decentralized economic mechanisms, it turned out to be important to know when one can construct an SDR for a collection of sets that cover the parameter space characterizing a finite number of economic agents. The condition of Theorem 1 is readily verifiable in that economic context. Theorems 2–5 give different characterizations of situations in which the collection of sets is a partition. This is of interest because partitions have special properties of informational efficiency.     

Generalizing the standard product rule of probability theory and Bayes's Theorem

In this paper the usual product rule of probability theory is generalized by relaxing the assumption that elements of sets are equally likely to be drawn. The need for such a generalization has been noted by Jeffreys [1998. Theory of Probability, 3rd ed, reprinted in Oxford classics Series, Oxford University Press (1st ed.,1939), Oxford. pp. 24–25], among others, in his work on an axiom system for scientific learning from data utilizing Bayes's Theorem. It is shown that by allowing probabilities of elements to be drawn to be different, generalized forms of the product rule and Bayes's Theorem are obtained that reduce to the usual product rule and Bayes's Theorem under certain assumptions that may be satisfactory in many cases encountered in practice in which the principle of insufficient reason is inadequate. Also, in comparing alternative hypotheses, allowing the prior odds to be random rather than fixed provides a useful generalization of the standard posterior odds.     

Multilateral negotiations and formation of coalitions

This paper analyses properties of games modeling multilateral negotiations leading to the formation of coalitions in an environment with widespread externalities. The payoff generated by each coalition is determined by an exogenous partition function (the parameter space). We show that in almost all games, except in a set of measure zero of the parameter space, the Markov perfect equilibrium value of coalitions and the state transition probability that describe the path of coalition formation is locally unique and stable. Therefore, comparative statics analysis are well-defined and can be performed using standard calculus tools. Global uniqueness does not hold in general, but the number of equilibria is finite and odd. In addition, a sufficient condition for global uniqueness is derived, and using this sufficient condition we show that there is a globally unique equilibrium in three-player superadditive games.     

Types of motions as proposed in the Dutch House of Representatives

This exploratory study provides an answer to the question what a coalition agreement means for negotiation by political parties in the House and what consequences this has for the motions submitted. Motions on environmental and immigration policy are compared at the time of two different governments. Based on the coalition agreements we estimate how much space for negotiation with regard to both issues and both periods is available. On that basis predictions are made regarding the numbers of submitted and passed motions. Moreover, a new classification is introduced in order to be able to group motions based on the intended purpose. Also predictions are made about this. The results show that, in line with expectations, fewer motions are proposed on issues where the negotiation space is limited, but this effect is not significant. However, there are significant findings with regard to motions that have passed. Where negotiation space is smaller, fewer motions pass than with respect to topics where the negotiation space is greater. As regards the different types of motions, the research gives unexpected, but interesting, results.     

Cores of effectivity functions and implementation theory

In a committee where cooperative voting occurs, effectivity functions describe the blocking power of coalitions. It is a binary relation that says for each coalition T and each subset of outcomes B whether or not T can force the final outcome within B. The corresponding cooperative stability notion generalizes the familiar core of a simple game. We study those effectivity functions yielding a non-empty core for all preference profiles, of which additive effectivity functions are an example. This proves to be closely related to implementation by means of the strong equilibrium concept.     

Investigating parental intention of using internet filter software

The objective of this study is to survey the usage of internet filter software for blocking inappropriate web contents in Taiwan, and also to investigate the precedent factors for adopting such a prevention tool. We surveyed 417 households with children/adolescents (aged below 16) and home internet access. Participants answered questions which were designed based on the framework of the decomposed theory of planned behavior. The structural equation model was implemented to find out the relationships among constructs. Results show that only one in seven families currently uses internet filter software for blocking inappropriate web contents in Taiwan. Furthermore, this study also shows that attitude, subjective norms, and perceived behavior control are all key factors to affect parental intention of adopting internet filter software. More specifically, compatibility, peer’s influence, self-efficacy, and facilitating conditions are four major precedent variables to influence parental intention via attitude, subjective norms, and perceived behavior control. Results obtained in this study suggest the urgency of prompting the use of filter software especially when no similar alternatives are available in the market. In addition, focusing on the promotion of product’s compatible features, the use of teachers’ opinions, and the establishment of supporting resources will highly increase parental intention of using internet filter software.     

Francesco Paolo Cantelli

Francesco Paolo Cantelli made fundamental contributions to the foundations of probability theory and to the clarification of different types of probabilistic convergence. He is remembered through the Borel–Cantelli Lemma, the Glivenko–Cantelli Theorem, and Cantelli's Inequality. He also made seminal contributions to actuarial science.     

The efficacy and efforts of interest groups in post elections policy formation

This paper presents a new model of interest groups and policy formation in the legislature. In our setting, the already given party ideological predispositions and power distribution determine the expected policy outcome. Our analysis applies to the case of un-enforced or enforced party discipline as well as to two-party and multi-party (proportional representation) electoral systems. The interest groups’ objective is to influence the outcome in their favor by engaging in a contest that determines the final decision in the legislature. Our first result clarifies how the success of an interest group hinges on the dominance of its ideologically closer party and, in general, the coalition/opposition blocks of parties under un-enforced party or coalition/opposition discipline. Such dominance is defined in terms of ideological inclination weighted by power. Our second result clarifies how the success of an interest group hinges on the dominance of its ideology in the ruling coalition (party) in a majoritarian system with enforced coalition (party) discipline. We then clarify under what condition an interest group prefers to direct its lobbying efforts to two parties or the two coalition and opposition blocks of parties under un-enforced discipline rather than to the members of the ruling coalition (party) under enforced discipline. The lobbying efforts under un-enforced and enforced party discipline are also compared. Finally, we clarify the effect of ideological predispositions and power on the efforts of the interest groups.     

The proportion of blocking coalitions in atomless economies

In this paper we investigate the number of coalitions that block a given non-competitive allocation. In an atomless economy with a finite number of types we identify coalition with its profile. Considering profiles π that represent coalitions with the same proportions of types as in the whole society, we prove that there is a ball B_π with π as its center so that ‘almost half’ of the profiles in B_π are blocking. This result is an analogous result to that of Mas-Colell (1978) who dealt with large finite markets.     

When does universal peace prevail? Secession and group formation in conflict

This paper analyzes secession and group formation in the general model of contests due to Esteban and Ray (1999). This model encompasses as special cases rent seeking contests and policy conflicts, where agents lobby over the choice of a policy in a one-dimensional policy space. We show that in both models the grand coalition is the efficient coalition structure and agents are always better off in the grand coalition than in a contest among singletons. Individual agents (in the rent seeking contest) and extremists (in the policy conflict) only have an incentive to secede when they anticipate that their secession will not be followed by additional secessions. Incentives to secede are lower when agents cooperate inside groups. The grand coalition emerges as the unique subgame perfect equilibrium outcome of a sequential game of coalition formation in rent seeking contests. Received: March 2004, Accepted: October 2004, JEL Classification: D72, D74 We thank Joan Maria Esteban, Kai Konrad, Debraj Ray, Stergios Skaperdas and two anonymous referees for helpful comments on the paper. We also benefitted from comments by seminar participants in Barcelona, Istanbul, Paris and WZB Berlin.     

Performance lies are hazardous to organizational health

Performance lies arise both from individual and from situational causes, but in this article, the attention is on situational causes. These are generally triggered by loyalty to the coalition, which is expressed through the continued use of performance lies. Because performance lies help create a boundary around the coalition that insulates its activities from top management, performance lies enable members of the coalition to exercise a greater degree of internal control. Naturally, such lies are dysfunctional, resulting in the avoidance of difficult issues and problems and compromising the organization's ability to adapt to a changing environment based on accurate information.     

Stable and efficient coalitional networks

We develop a theoretical framework that allows us to study which bilateral links and coalition structures are going to emerge at equilibrium. We define the notion of coalitional network to represent a network and a coalition structure, where the network specifies the nature of the relationship each individual has with her coalition members and with individuals outside her coalition. To predict the coalitional networks that are going to emerge at equilibrium we propose the concepts of strong stability and of contractual stability. Contractual stability imposes that any change made to the coalitional network needs the consent of both the deviating players and their original coalition partners. Requiring the consent of coalition members under the simple majority or unanimity decision rule may help to reconcile stability and efficiency. Moreover, this new framework can provide insights that one cannot obtain if coalition formation and network formation are tackled separately and independently.     

Time horizons matter: the hazard rate of coalition governments and the size of government

This study examines how coalition governments affect the size of government, measured by total central government expenditure as a share of GDP. Existing studies suggest that the presence of multiple political parties within ruling coalitions generate common pool resource problems or bargaining inefficiencies which, in turn, leads to more government spending when coalition governments are in office. We demonstrate that coalition governments have shorter time horizons than single party governments and use that finding to motivate a simple formal model. The model shows that coalition governments have greater incentives to increase government spending because of a lower discount factor in office. Results from empirical models estimated on a global sample of 111 democracies between 1975 and 2007 provide strong statistical support for the aforementioned theoretical prediction. The empirical results remain robust when we control for alternative explanations, employ different estimation techniques, and use different measures of government spending.     

Optimal strategic alliance in multi-echelon supply chains with open innovation

We propose a game-theoretic approach to examine several possible coalition strategies in a four-echelon supply chain consisting of a supplier, manufacturer, wholesaler, and retailer. A solitude model is used to probe the role of learning in quality improvements, and experimental design is conducted to evaluate all possible supply chain coalition strategies between echelons. The novelty of this study is the comprehensive evaluation of knowledge-sharing strategies in collaborative supply chains. The results confirm that the Delta model with a coalition among a supplier, manufacturer, and retailer is the best strategy.     

The hybrid equilibria and core selection in exchange economies with externalities

This paper introduces a hybrid equilibrium concept that combines the elements of cooperative and non-cooperative behaviors in an exchange economy with externalities. For a fixed coalition structure (or a partition of traders), the hybrid equilibrium is a price and consumption bundle such that each coalition chooses a core solution from its budget set and the consumption bundles are feasible. It becomes the competitive equilibrium when the position is the finest, and it selects a core allocation when the partition is the coarsest. The paper provides sufficient conditions for the existence of a hybrid equilibrium for any coalition structure.     

Aggregate expectations under the stable laws

Following Lucas, expectations have become central to macroeconomic theory. Empirical implementations generally start from tendency surveys, where respondents indicate the expected direction of change. Carlson and Parkin, and others, turn this into quantitative measures by assuming aggregate expectations followed a normal distribution. These show signs of irrationality. However, the Central Limit Theorem requires only that such a distribution lie in the class of ‘stable probability laws’. Indeed, the Lucas information assumptions, and evidence on individual survey responses, argue against the limiting case of normality. Experiments on European Business Surveys show that substitution of skewed stable distributions can eliminate symptoms of irrationality previously found in survey-based expectations measures.     

Endogenous coalition formation in contests

This paper analyzes coalition formation in a model of contests with linear costs. Agents first form groups and then compete by investing resources. Coalitions fight for a prize that is assumed to be subject to rivalry, so its value is non-increasing in the size of the group that obtains it. This formulation encompasses as particular cases some models proposed in the rent-seeking literature. We show that the formation of groups generates positive spillovers and analyze two classes of games of coalition formation. A contest among individual agents is the only stable outcome when individual defections leave the rest of the group intact. More concentrated coalition structures, including the grand coalition, are stable when groups collapse after a defection, provided that rivalry is not too strong. Results in a sequential game of coalition formation suggest that there exists a non-monotonic relationship between the level of underlying rivalry and the level of social conflict.

“If men were supplied with every thing in the same abundance, justice and injustice would be equally unknown among mankind.” David Hume (1740), A Treatise of Human Nature

I thank Luis Corchón, Joan Esteban, Michelle Garfinkel and József Sákovics for their comments and suggestions on the paper.     

A formulation of the aggregation problem in terms of coalition and bargaining theory

The object of this paper is to demonstrate in economic terms the equivalence of the problem of aggregation in input-output analysis with coalition and bargaining problems. Depending on the specific norm for aggregation it is shown that the aggregation criterion and the coalition forming criterion in an n-person game leads to a broadly similar situation in the market sense given that the market operates to that criterion. It is also shown that a mathematical analogue to this formulation may be obtained via the techniques of geometric programming.