On some further properties of nonzero-sum diffential games

Optimality principle and open loop-closed loop control relations in nonzero-sum differential game

Multistage communication with and without verifiable types

We survey the main results on strategic information transmission, which is often referred to as ``persuasion" when types are verifiable and as ``cheap talk" when they are not. In the simplest ``cheap talk'' model, an informed player sends a single message to a receiver who makes a decision. The players' utilities depend on the sender's information and the receiver's decision, but not on the sender's message. Furthermore, the messages that are available to the sender do not depend on his true information. As is well-known, such a unilateral ``cheap talk" can affect the sender's decision at equilibrium. In a more general model, both players can exchange simultaneous costless messages during several stages before the final decision. The utility functions are unchanged. Multistage conversation allows the players to reach more equilibrium outcomes, which possibly Pareto dominate the original ones. More precisely, the set of equilibrium outcomes of long cheap talk games is fully characterized; it increases with the number of communication stages and can become even larger if no deadline is imposed. Concentrating on cheap talk is not appropriate if the informed player can influence the decision maker by producing unfalsifiable documents. In order to capture this possibility formally, one assumes that the informed player's set of messages depends on his private information. The literature has mostly dealt with unilateral persuasion. But multistage, bilateral communication enables the players to reach more equilibrium outcomes in the case of verifiable types as in the case of unverifiable ones. Equilibria of long persuasion games are fully characterized when information can be certified at any precision level.Cheap talk; certification; incomplete information; information transmission; jointly controlled lotteries; verifiable types

Correlated equilibria and communication in games.

Analyse bayésienne; Théorie des jeux; Information privée;

Recursive Inspection Games

We consider a sequential inspection game where an inspector uses a limited number of inspections over a larger number of time periods to detect a violation (an illegal act) of an inspectee. Compared with earlier models, we allow varying rewards to the inspectee for successful violations. As one possible example, the most valuable reward may be the completion of a sequence of thefts of nuclear material needed to build a nuclear bomb. The inspectee can observe the inspector, but the inspector can only determine if a violation happens during a stage where he inspects, which terminates the game; otherwise the game continues. Under reasonable assumptions for the payoffs, the inspector's strategy is independent of the number of successful violations. This allows to apply a recursive description of the game, even though this normally assumes fully informed players after each stage. The resulting recursive equation in three variables for the equilibrium payoff of the game, which generalizes several other known equations of this kind, is solved explicitly in terms of sums of binomial coefficients. We also extend this approach to non-zero-sum games and, similar to Maschler (1966), "inspector leadership" where the inspector commits to (the same) randomized inspection schedule, but the inspectee acts legally (rather than mixes as in the simultaneous game) as long as inspections remain.Comment: final version for Mathematics of Operations Research, new Theorem

On values of repeated games with signals

We study the existence of different notions of value in two-person zero-sum repeated games where the state evolves and players receive signals. We provide some examples showing that the limsup value (and the uniform value) may not exist in general. Then we show the existence of the value for any Borel payoff function if the players observe a public signal including the actions played. We also prove two other positive results without assumptions on the signaling structure: the existence of the $\sup$ value in any game and the existence of the uniform value in recursive games with nonnegative payoffs.Comment: Published at http://dx.doi.org/10.1214/14-AAP1095 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Improving Efficiency and Scalability of Sum of Squares Optimization: Recent Advances and Limitations

It is well-known that any sum of squares (SOS) program can be cast as a semidefinite program (SDP) of a particular structure and that therein lies the computational bottleneck for SOS programs, as the SDPs generated by this procedure are large and costly to solve when the polynomials involved in the SOS programs have a large number of variables and degree. In this paper, we review SOS optimization techniques and present two new methods for improving their computational efficiency. The first method leverages the sparsity of the underlying SDP to obtain computational speed-ups. Further improvements can be obtained if the coefficients of the polynomials that describe the problem have a particular sparsity pattern, called chordal sparsity. The second method bypasses semidefinite programming altogether and relies instead on solving a sequence of more tractable convex programs, namely linear and second order cone programs. This opens up the question as to how well one can approximate the cone of SOS polynomials by second order representable cones. In the last part of the paper, we present some recent negative results related to this question.Comment: Tutorial for CDC 201

Nonzero-sum differential games - Concepts and models

Differential games controlling inputs to single dynamic system as extension of optimal control theor

Long Persuasion Games

This paper characterizes geometrically the set of all Nash equilibrium payoffs achievable with unmediated communication in persuasion games, i.e., games with an informed expert and an uninformed decisionmaker in which the expert's information is certifiable. The first equilibrium characterization is provided for unilateral persuasion games, and the second for multistage, bilateral persuasion games. As in Aumann and Hart (2003), we use the concepts of diconvexification and dimartingale. A leading example illustrates both geometric characterizations and shows how the expert, whatever his type, can increase his equilibrium payoff compared to all equilibria of the unilateral persuasion game by delaying information certification.cheap talk, communication, diconvexification, dimartingale, disclosure of certifiable information, jointly controlled lotteries, long conversation, persuasion, verifiable types

Nondominated equilibrium solutions of multiobjective two-person nonzero-sum games in normal and extensive forms

In this paper, we review the development of studies on multiobjective noncooperative games, and particularly we focus on nondominated equilibrium solutions in multiobjective two-person nonzero-sum games in normal and extensive forms. After outlining studies related to multiobjective noncooperative games, we treat multiobjective two-person nonzero-sum games in normal form, and a mathematical programming problem yielding nondominated equilibrium solutions is shown. As for extensive form games, we first provide a game representation of the sequence form, and then formulate a mathematical programming problem for obtaining nondominated equilibrium solutions