Amparo Urbano

Computational Complexity and Communication: Coordination in Two-Player Games

The main contribution of this paper is the development and application of cryptographic techniques to the design of strategic communication mechanisms. One of the main assumptions in cryptography is the limitation of the computational power available to agents. We introduce the concept of limited computational complexity, and by borrowing results from cryptography, we construct a communication protocol to establish that every correlated equilibrium of a two-person game with rational payoffs can be achieved by means of computationally restricted unmediated communication. This result provides an example in game theory where limitations of computational abilities of players are helpful in solving implementation problems. More specifically, it is possible to construct mechanisms with the property that profitable deviations are too complicated to compute. Copyright The Econometric Society 2002.

The manufacturers' choice of distribution policy under successive duopoly

We examine an asymmetric noncooperative game between two manufacturers selecting the number of retailers who can distribute their products. In deciding whether to distribute through one or both retailers, there are two conflicting effects: the output expansion effect, because the product is sold in more outlets; and the competitive effect, associated with the introduction of intrabrand competition. Product differentiation and demand asymmetries between the two products determine which of these two effects dominates the other. When product differentiation is strong and brand asymmetry is moderate, both manufacturers distribute through both retailers in equilibrium. However, when both product differentiation and brand asymmetry are weak, exclusive dealing through a single retailer is the equilibrium. Perhaps the most interesting finding is that there also exist asymmetric equilibria in which one manufacturer distributes through both retailers but the other manufacturer distributes through one retailer. These equilibria can arise when both product differentiation and brand asymmetry are strong.

Duopoly experimentation: Cournot competition

Abstract This paper analyzes learning behavior in an industry facing uncertainty. We consider a duopoly game where firms have imperfect information about market demand and they learn through observing market prices. The main body of our study consists of showing how firms make the price a more informative signal through their experimental behavior, and how this behavior compares to its monopoly counterpart. We extend previous analysis to the case where the demand unknown parameter takes values on the real line. We also find that experimentation under Cournot duopoly is smaller than under monopoly whenever the demands unknown parameter is sufficiently precise.

Unmediated Communication In Repeated Games With Imperfect Monitoring

We show that any correlated equilibrium payoff of two-player repeated games with imperfect monitoring and without discounting can be reached as the Nash equilibrium payoff of the game extended by a universal mechanism of unmediated communication. This result holds regardless the particular concept of equlibrium involved (upper, lower, Banach or uniform equlibrium). The communication mechanism is built up by using commutative one-way functions. These functions are designed with the help of cryptographic tools.

A Model of Multiproduct Price Competition

Strategic interaction in oligopolistic markets has been extensively studied in the literature. This literature deals mostly with the case of multiple firms which produce a homogeneous good or goods that are perfect substitutes. In this paper we provide a simple model of price competition in a multiproduct oligopoly market. We find that apure strategy equilibrium exists and that the equilibrium consumption sets are efficient since they maximize the total social surplus. If the willingness to pay function of the consumer is convex, the set of equilibrium prices coincides with the core of a related game and the firms extract total industry surplus. If it is concave, the only equilibrium price of a product is its marginal contribution to the consumers total willingness to pay. If the products are perfect substitutes we obtain the standard Bertrand equilibrium.

Are social and entrepreneurial attitudes compatible?: A behavioral and self‐perceptional analysis

Purpose – The aim of this paper is to analyze the compatibility between entrepreneurial and social attitudes. Specifically, we analyze if subjects with a more developed economic entrepreneurial attitude exhibit a less social attitude. Design/methodology/approach – Our methodology integrates an economic experimental approach with a standard entrepreneurial intention questionnaire to analyze the interaction between entrepreneurial and social self-perceptions and behavior. Findings – There is empirical evidence that experimental entrepreneurial behavior (characterized by detecting an opportunity and accepting risk to take an economic advantage from it in laboratory experiments) reduces the incentive for social behavior. However, this effect does not appear if just self-perceptions instead of experimental behaviors are considered. Research limitations/implications – The social attitude of entrepreneurs may be overestimated in those empirical research studies based only on data obtained from entrepreneurs’ answers to hypothetical questions in a survey. Originality/value - To the best of our knowledge, this is the first paper presenting a laboratory experiment to represent the key features of entrepreneurial behavior instead of a case-control analysis to set differences in the experimental behavior of sub-samples of subjects defined in terms of their entrepreneurial motivation or experience.

Pure Component Pricing in a Duopoly

In this paper, we focus on price competition between several multiproduct firms which produce differentiated systems, each consisting of two complementary products. It is shown here that if firms are restricted to pure component pricing (bundling is not allowed) whenever components produced are compatible, pure strategy equilibrium may not exist. With the use of bundling strategies, pure strategy equilibrium always exists. For the pure component pricing case we provide a full characterization for the existence of a pure strategy equilibrium.

Product Line Choice in Retail Duopoly

This paper develops a successive duopoly model to identify conditions under which differentiated retailers that compete in quantities, when deciding on the range of brands to offer, will carry overlapping product lines. They will do so when retail margins on each brand are not too asymmetric. Otherwise, the less profitable brand is foreclosed from the market. It is shown that welfare increases if the upstream industry is perfectly competitive, even though fewer brands may be sold. With price competition though, exclusive dealing arises when retailers are not too differentiated and in-store competition is sufficiently intense.

Entry and espionage with noisy signals

We analyze the effect of industrial espionage on entry deterrence. We consider a monopoly incumbent who may expand capacity to deter entry, and a potential entrant who owns an Intelligence System. The Intelligence System (IS) generates a noisy signal based on the incumbentʼs actions. The potential entrant uses this signal to decide whether or not to enter the market. The incumbent may signal-jam to manipulate the likelihood of the noisy signals and hence affect the entrantʼs decisions. If the precision of the IS is commonly known, the incumbent benefits from his rivalʼs espionage. Actually, he benefits more the higher is the precision of the IS while the spying entrant is worse off with an IS of relatively high quality. When the IS quality is private information of the entrant, the incumbent is better off with an IS of high expected precision while the entrant benefits from one of high quality. In this case espionage makes the market more competitive.

Pragmatic languages with universal grammars

This paper constructs the equilibrium for a specific code that can be seen as a “universal grammar” in a class of common interest Sender–Receiver games where players communicate through a noisy channel. We propose a Senderʼs signaling strategy which does not depend on either the game payoffs or the initial probability distribution. The Receiverʼs strategy partitions the set of possible sequences into subsets, with a single action assignment to each of them. The Senderʼs signaling strategy is a Nash equilibrium, i.e. when the Receiver responds best to the Senderʼs strategy, the Sender has no incentive to deviate. An example shows that a tie-breaking decoding is crucial for the block-coding strategy to be an equilibrium. Efficiency is analyzed by comparing how close ex-ante expected payoffs are to those of noiseless communication. Moreover, we study how long communication should be to achieve a given payoff-approximation.