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.

This paper considers a fírm facing an uncertain demand curve. The firm can experimentally adjust its output in order to gain information that will increase expected future profits. We examine two basic questions. Unde= what conditions is it worthwhile for the fírm to experiment? How does the firm adjust its output away from the myopic optimum to exploit its ability to experiment? Two necessary conditions are established for experimentation to occur, involving requirements that experimentation be informative and that information be valuable. Conditions are then established for experimentation to induce the firm to increase or decrease quantity. These results, which contain severa1 previous analyses as special cases, provide an understanding ' t of experimentation that will be useful in a number of applications.

We show the role of unmediated talk with computational complexity bounds as both an information transmission and a coordination device for the class of two-player games with incomplete information and rational parameters. We prove that any communication equilibrium payoff of such games can be reached as a Bayesian-Nash equilibrium payoff of the game extended by a two phase universal mechanism of interim computationally restricted pre-play communication. The communication protocols are designed with the help of modern cryptographic tools. A familiar context in which our results could be applied is bilateral trading with incomplete information. Copyright Springer-Verlag Berlin/Heidelberg 2004Computational complexity, Unmediated communication, Correlated equilibrium, Bayesian-Nash equilibrium.,

We analyze industrial espionage in the context of entry deterrence. We consider a monopoly incumbent, who may expand capacity to deter entry, and a potential entrant who owns an inaccurate Intelligence System. The Intelligence System generates a noisy signal on incumbent's actions and the potential entrant decides whether to enter based on this signal. If the precision of the Intelligence System is commonly known, the incumbent will signal-jam to manipulate the distribution of likely signals and hence the entrant's decisions. Therefore, the incumbent will benefit from his rival's espionage. In contrast, the spying firm (the entrant) will typically gain if the espionage accuracy is sufficiently high and privately known by her. In this setting, the market will be more competitive under espionage.

No abstract