Two-player games : a reduction

The general idea of the proof is to define a class of sets, the solvable sets, which can safely be thought of as absorbing states.stochastic games; recursive games

Stochastic Games : recent results

Nous présentons des résultats récents sur les jeux stochastiques finis. Ce texte est à paraître dans le Handbook of Game Theory, vol 3., eds. R.J. Aumann et S. HartJeux stochastiques

Random walks and voting theory

Voters' preferences depend on the available information. Following Case-Based Decision Theory, we assume that this information is processed additively. We prove that the collective preferences deduced from the individual ones through majority vote cannot be arbitrary, as soon as a winning quota is required. The proof is based on a new result on random walks.voting theory; quotas; random walks

Multiple solutions under quasi-exponential discounting

We consider a group or committee that faces a binary decision under uncertainty. Each member holds some private information. Members agree which decision should be taken in each state of nature, had this been known, but they may attach different values to the two types of mistake that may occur. Most voting rules have a plethora of uninformative equilibria, and informative voting may be incompatible with equilibrium. We analyze an anonymous randomized majority rule that has a unique equilibrium. This equilibrium is strict, votes are informative, and the equilibrium implements the optimal decision with probability one in the limit as the committee size goes to infinity. We show that this also holds for the usual majority rule under certain perturbations of the behavioral assumptions: (i) a slight preference for voting according to one's conviction, and (ii) transparency and a slight preference for esteem. We also show that a slight probability for voting mistakes strengthens the incentive for informative voting.: time-consistency, hyperbolic discounting, stochastic dynamic programming, multiplicity, uniqueness.

Uniform Value in Recursive Games

We address the problem of existence of the uniform value in recursive games. We give two existence results. (i) The uniform value is shown to exist if the state space is countable, the action sets are finite and if, for some a > 0, there are finitely many states in which the limsup value is less than a. (ii) For games with non-negative payoff function, it is sufficient that the action set of player 2 is finite. The finiteness assumption can be further weakened.

Majority vote following a debate

Voters determine their preferences over alternatives based on cases (or arguments) that are raised in the public debate. Each voter is characterized by a matrix, measuring how much support each case lends to each alternative, and her ranking is additive in cases. We show that the majority vote in such a society can be any function from sets of cases to binary relations over alternatives. A similar result holds for voting with quota in the case of two alternatives.Case-based decision theory; voting theory; debates

Deterministic Multi-Player Dynkin Games

A multi-player Dynkin game is a sequential game in which at every stage one of the players is chosen, and that player can decide whether to continue the game or to stop it, in which case all players receive some terminal payoff. We study a variant of this model, where the order by which players are chosen is deterministic, and the probability that the game terminates once the chosen player decides to stop may be strictly less than one. We prove that a subgame-perfect e-equilibrium in Markovian strategies exists. If the game is not degenerate this e-equilibrium is actually in pure strategies.n-player games; stopping games; subgame perfect equilibrium

Perturbed Markov Chains

We obtain results on the sensitivity of the invariant measure and other statistical quantities of a Markov chain with respect to perturbations of the transition matrix. We use graph-theoretic techniques, in contrast with the matrix analysis techniques previously used.perturbed markov chains; conductance

Stopping games: recent results

Ce texte présente des résultats récents sur les jeux d'arrêts. Il a été préparé pour l'ouvrage collectif à paraître, Annals of Dynamic Games, ed A. NowakJeux d'arrêt;Valeur;Jeux stochastiques