Core-stable Rings in Auctions with Independent Private Values

We propose a semi-cooperative game theoretic approach to check whether a given coalition is stable in a Bayesian game with independent private values. The ex ante expected utilities of coalitions, at an incentive compatible (noncooperative) coalitional equilibrium, describe a (cooperative) partition form game. A coalition is core-stable if the core of a suitable characteristic function, derived from the partition form game, is not empty. As an application, we study collusion in auctions in which the bidders’ final utility possibly depends on the winner’s identity. We show that such direct externalities offer a possible explanation for cartels’ structures (not) observed in practice.auctions, Bayesian game, collusion, core, partition function game

Instant Efficient Pollution Abatement under Non-Linear Taxation and Asymmetric Information: The Differential Tax Revisited

This paper analyzes incentives for polluting firms to exchange abatement cost information under the non-linear pollution tax scheme (‘differential tax’) introduced by Kim and Chang [J. Regul. Econom. 5, 1993, 193-197]. It shows that polluting firms have - under mild conditions - an incentive to join a coalition whose members mutually truthfully exchange information as well as commit themselves with respect to their abatement decisions. As a result, the differential tax triggers instantly - i.e. no abatement adaptation is needed – efficient abatement levels without the regulator knowing marginal abatement costs. Consequently, this paper shows that differential taxation results in lower social costs than traditional non-linear taxation which triggers efficient emissions only after a period of non-efficient abatement.Externalities, Pollution taxes, Coalition formation, Non-linear taxation, Asymmetric information, Co-operative game theory

Core-stable rings in auctions with independent private values.

We propose a semi-cooperative game theoretic approach to check whether a given coalition is stable in a Bayesian game with independent private values. The ex ante expected utilities of coalitions, at an incentive compatible (noncooperative) coalitional equilibrium, describe a (cooperative) partition form game. A coalition is core-stable if the core of a suitable characteristic function, derived from the partition form game, is not empty. As an application, we study collusion in auctions in which the bidders' final utility possibly depends on the winner's identity. We show that such direct externalities offer a possible explanation for cartels'structures (not) observed in practice.Core; partition function game; Collusion; Auctions; Bayesian game;

Leadership in Multi-sided Markets

I analyze the role of leadership in multi-sided markets as online advertising. Search and display advertising are better characterized by (respectively) quantity and price competition. A platform that reached dominance in search may have an incentive to limit services to consumers to be aggressive with the advertisers, to exploit its scale in search to build barriers to entry, or to adopt click-weighted auctions to manipulate the pricing of sponsored links. On the other side, a dominant platform in display advertising may increase the rewards of content providers to increase prices on advertisers, or may adopt exclusive clauses to predate on other platforms.Multisided markets, Leadership, Dominance

Economic and Environmental Effectiveness of a Technology-based Climate Protocol

The present stalemate in climate negotiations has led policy analysts and economists to explore the possible emergence of alternative climate regimes. This paper explores the idea of replacing international cooperation on greenhouse gas emission control with international cooperation on climate-related technological innovation and diffusion. This idea – recently proposed among others by Barrett (2001) and Benedick (2001) – is based on the insight that incentives to free-ride are much smaller in the case of technological cooperation than in the case of cooperation on emission control. This paper provides a first applied game theory analysis of a technology-based climate protocol by assessing: (i) the self-enforcingness (namely, the absence of incentives to free ride) of the coalition that would form when countries negotiate on climate-related technological cooperation; (ii) the environmental effectiveness of a technology-based climate protocol. The analysis is carried out by using a model in which endogenous and induced technical change are explicitly modelled and in which international technological spillovers are also quantified. The results of our analysis partly support Barrett’s and Benedick’s conjecture. On the one hand, a self-enforcing agreement is more likely to emerge when countries cooperate on environmental technological innovation and diffusion than when they cooperate on emission abatement. However, technological cooperation – without any commitment to emission control – may not lead to a sufficient abatement of greenhouse gas concentrations.Agreements, Climate, Incentives, Technological change, Policy

The Cost of Sybils, Credible Commitments, and False-Name Proof Mechanisms

Consider a mechanism that cannot observe how many players there are directly, but instead must rely on their self-reports to know how many are participating. Suppose the players can create new identities to report to the auctioneer at some cost $c$. The usual mechanism design paradigm is equivalent to implicitly assuming that $c$ is infinity for all players, while the usual Sybil attacks literature is that it is zero or finite for one player (the attacker) and infinity for everyone else (the 'honest' players). The false-name proof literature largely assumes the cost to be 0. We consider a model with variable costs that unifies these disparate streams. A paradigmatic normal form game can be extended into a Sybil game by having the action space by the product of the feasible set of identities to create action where each player chooses how many players to present as in the game and their actions in the original normal form game. A mechanism is (dominant) false-name proof if it is (dominant) incentive-compatible for all the players to self-report as at most one identity. We study mechanisms proposed in the literature motivated by settings where anonymity and self-identification are the norms, and show conditions under which they are not Sybil-proof. We characterize a class of dominant Sybil-proof mechanisms for reward sharing and show that they achieve the efficiency upper bound. We consider the extension when agents can credibly commit to the strategy of their sybils and show how this can break mechanisms that would otherwise be false-name proof

The EU Emissions Trading Scheme. Allowance Prices, Trade Flows, Competitiveness Effects

The upcoming European Emissions Trading Scheme (ETS) is one of the more controversial climate policy instruments. Predictions about its likely impact and its performance can at present only be made to a certain degree. As long as the National Allocations Plans are not finally settled the overall supply of allowances is not determined. In this paper we will identify key features and key impacts of the EU ETS by scanning the range of likely allocation plans using the simulation model DART. The analysis of the simulation results highlights a number of interesting details in terms of allowance trade flows between member countries, of allowance prices, and in terms of the role of the accession countries in the ETS.EU Emissions trading scheme, Kyoto targets, Computable general equilibrium model, DART

Comparative Financial Systems: A Survey

What is a Financial System? The purpose of a financial system is to channel funds from agents with surpluses to agents with deficits. In the traditional literature there have been two approaches to analyzing this process. The first is to consider how agents interact through financial markets. The second looks at the operation of financial intermediaries such as banks and insurance companies. Fifty years ago, the financial system could be neatly bifurcated in this way. Rich households and large firms used the equity and bond markets, while less wealthy households and medium and small firms used banks, insurance companies and other financial institutions. Table 1, for example, shows the ownership of corporate equities in 1950. Households owned over 90 percent. By 2000 it can be seen that the situation had changed dramatically. By then households held less than 40 percent, nonbank intermediaries, primarily pension funds and mutual funds, held over 40 percent. This change illustrates why it is no longer possible to consider the role of financial markets and financial institutions separately. Rather than intermediating directly between households and firms, financial institutions have increasingly come to intermediate between households and markets, on the one hand, and between firms and markets, on the other. This makes it necessary to consider the financial system as an irreducible whole. The notion that a financial system transfers resources between households and firms is, of course, a simplification. Governments usually play a significant role in the financial system. They are major borrowers, particularly during times of war, recession, or when large infrastructure projects are being undertaken. They sometimes also have significant amounts of funds. For example, when countries such as Norway and many Middle Eastern States have access to large amounts of natural resources (oil), the government may acquire large trust funds on behalf of the population. In addition to their roles as borrowers or savers, governments usually play a number of other important roles. Central banks typically issue fiat money and are extensively involved in the payments system. Financial systems with unregulated markets and intermediaries, such as the US in the late nineteenth century, often experience financial crises (Gorton (1988) and Calomiris and Gorton (1991)). The desire to eliminate these crises led many governments to intervene in a significant way in the financial system. Central banks or some other regulatory authority are charged with regulating the banking system and other intermediaries, such as insurance companies. So in most countries governments play an important role in the operation of financial systems. This intervention means that the political system, which determines the government and its policies, is also relevant for the financial system. There are some historical instances where financial markets and institutions have operated in the absence of a well-defined legal system, relying instead on reputation and other implicit mechanisms. However, in most financial systems the law plays an important role. It determines what kinds of contacts are feasible, what kinds of governance mechanisms can be used for corporations, the restrictions that can be placed on securities and so forth. Hence, the legal system is an important component of a financial system. A financial system is much more than all of this, however. An important pre-requisite of the ability to write contracts and enforce rights of various kinds is a system of accounting. In addition to allowing contracts to be written, an accounting system allows investors to value a company more easily and to assess how much it would be prudent to lend to it. Accounting information is only one type of information (albeit the most important) required by financial systems. The incentives to generate and disseminate information are crucial features of a financial system. Without significant amounts of human capital it will not be possible for any of these components of a financial system to operate effectively. Well-trained lawyers, accountants and financial professionals such as bankers are crucial for an effective financial system, as the experience of Eastern Europe demonstrates. The literature on comparative financial systems is at an early stage. Our survey builds on previous overviews by Allen (1993), Allen and Gale (1995) and Thakor (1996). These overviews have focused on two sets of issues. Normative: How effective are different types of financial systems at various functions? Positive: What drives the evolution of the financial system? The first set of issues of considered in sections 2-6, which focus on issues of investment and saving, growth, risk sharing, information provision and corporate governance, respectively. Section 7 considers the influence of law and politics on the financial system while Section 8 looks at the role financial crises have had in shaping the financial system. Section 9 contains concluding remarks.