We identify a universal type space of possible interdependent (expected utility) preferences of a group of agents satisfying two criteria. First, a type consists of a “detail free” description, in a natural language, of the agents’ interdependent preferences. Second, distinct types in the universal type space must be “strategically distinguishable” in the sense that there must exist a mechanism where those types are guaranteed to behave differently in equilibrium.
Our results generalize and unify results of Abreu and Matsushima (1992b) (who characterized strategic distinguishability on fixed finite type spaces) and Dekel, Fudenberg, and Morris (2006), (2007) (who characterized strategic distinguishability on type spaces without preference uncertainty and thus without interdependent preferences).
A universal type space of interdependent expected utility preference types is constructed from higher-order preference hierarchies describing (i) an agent’s (unconditional) preferences over a lottery space; (ii) the agent’s preference over Anscombe-Aumann acts conditional on the unconditional preferences; and so on.
Two types are said to be strategically indistinguishable if they have an equilibrium action in common in any mechanism that they play. We show that two types are strategically indistinguishable if and only if they have the same preference hierarchy. We examine how this result extends to alternative solution concepts and strategic relations between types.
We study agents whose expected utility preferences are interdependent for informational or psychological reasons. We characterize when two types can be “strategically distinguished” in the sense that they are guaranteed to behave differently in some finite mechanism. We show that two types are strategically distinguishable if and only if they have different hierarchies of interdependent preferences. The same characterization applies for rationalizability, equilibrium, and any interim solution concept in between. Our results generalize and unify results of Abreu and Matsushima (1992), who characterize strategic distinguishability on fixed finite type spaces, and Dekel, Fudenberg, and Morris (2006), (2007), who characterize strategic distinguishability without interdependent preferences.
We investigate the role of market transparency in repeated first-price auctions. We consider a setting with private and independent values across bidders. The values are assumed to be perfectly persistent over time.
We analyze the first-price auction under three distinct disclosure regimes regarding the bid and award history. Of particular interest is the minimal disclosure regime, in which each bidder only learns privately whether he won or lost the auction at the end of each round. In equilibrium, the winner of the initial auction lowers his bids over time, while losers keep their bids constant, in anticipation of the winner’s lower future bids. This equilibrium is efficient, and all information is eventually revealed. Importantly, this disclosure regime does not give rise to pooling equilibria.
We contrast the minimal disclosure setting with the case in which all bids are public, and the case in which only the winner’s bids are public. In these settings, an inefficient pooling equilibrium with low revenues always exists with a sufficiently large number of bidders.
We investigate the role of market transparency in repeated first-price auctions. We consider a setting with independent private and persistent values. We analyze three distinct disclosure regimes regarding the bid and award history. In the minimal disclosure regime each bidder only learns privately whether he won or lost the auction. In equilibrium the allocation is efficient and the minimal disclosure regime does not give rise to pooling equilibria. In contrast, in disclosure settings where either all or only the winner’s bids are public, an inefficient pooling equilibrium with low revenues exists.
We investigate the role of market transparency in repeated first-price auctions. We consider a setting with independent private and persistent values. We analyze three distinct disclosure regimes regarding the bid and award history. In the minimal disclosure regime each bidder only learns privately whether he won or lost the auction. In equilibrium the allocation is efficient and the minimal disclosure regime does not give rise to pooling equilibria. In contrast, in disclosure settings where either all or only the winner’s bids are public, an inefficient pooling equilibrium with low revenues exists.
We survey the recent literature on designing auctions and mechanisms for dynamic settings. Two settings are considered: those with a dynamic population of agents or buyers whose private information remains fixed throughout time; and those with a fixed population of agents or buyers whose private information changes across time. Within each of these settings, we discuss both efficient (welfare-maximizing) and optimal (revenue-maximizing) mechanisms.
We develop a model with many heterogeneous advertisers (products) and advertising markets (media). Each advertiser has a different consumer segment for its product, and each medium has a different ability to target advertisement messages. We characterize the competitive equilibrium in the media markets and investigate the role of targeting for the price and allocation of advertisements across media markets.
An increase in the targeting ability leads to an increase in the total number of purchases (matches), and hence in the social value of advertisements. Yet, an improved targeting ability also increases the concentration of advertising firms in each market. Surprisingly, we find that the equilibrium price for advertisements is decreasing in the targeting ability over a large range of parameter values.
We trace out the implications of targeting for competing media markets. We distinguish offline and online media by their targeting ability: low versus high. We show that competition by an online medium lowers the revenue of the offline medium more than competition by another offline medium of the same size.
We survey the recent literature on designing auctions and mechanisms for dynamic settings. Two settings are considered: those with a dynamic population of agents whose private information remains fixed throughout time; and those with a fixed population of agents whose private information changes across time. Within each of these settings, we discuss both efficient (welfare-maximizing) and optimal (revenue-maximizing) mechanisms.
We develop a model with many advertisers (products) and many advertising markets (media). Each advertiser sells to a different segment of consumers, and each medium has a different ability to target advertising messages. We characterize the competitive equilibrium in the media markets and evaluate the implications of targeting in advertising markets.
An increase in the targeting ability leads to an increase in the total number of purchases (matches), and hence in the social value of advertising. Yet, an improved targeting ability also increases the concentration of firms advertising in each market. Surprisingly, we then find that the equilibrium price of advertisements is first increasing, then decreasing in the targeting ability.
We trace out the implications of targeting for competing media. We distinguish offline and online media by their targeting ability: low versus high. As consumers, relative exposure to online media increases, the revenues of offline media decrease, even though the price of advertising might increase.
This note studies (full) implementation of social choice functions under complete information in (correlated) rationalizable strategies. The monotonicity condition shown by Maskin (1999) to be necessary for Nash implementation is also necessary under the more stringent solution concept. We show that it is also sufficient under a mild “no worst alternative” condition. In particular, no economic condition is required.
We consider the implementation of social choice functions under complete information in rationalizable strategies. A strict (and thus stronger) version of the monotonicity condition introduced by Maskin (1999) is necessary under the solution concept of rationalizability. Assuming the social choice function is responsive (i.e., it never selects the same outcome in two distinct states), we show that it is also sufficient under a mild “no worst alternative” condition. In particular, no economic condition is required. We also discuss how our results extend when the social choice function is not responsive.