One against all in the fictitious play process

There are only few "positive" results concerning multi-person games with the fictitious play property, that is, games in which every fictitious play process approaches the set of equilibria. In this paper we chararcterize classes of multi-person games with the fictitious play property. We consider an (n+1) player game {0,1,2,...,n} based on n two-person sub-games. In each of these sub-games player 0 plays against one of the other players. Player 0 is regulated, so that he must choose the same strategy in all n sub-games. we show that if all sub-games are either zero-sum ganes, weighted potential games, or games with identical payoff functions, then the fictitious play property holds for the associated game.

BEST-OF-THREE ALL-PAY AUCTIONS

We study a three-stage all-pay auction with two players in which the ?rst player to win two matches wins the best-of-three all-pay auction. The players have values of winning the contest and may have also values of losing, the latter depending on the stage in which the contest is decided. It is shown that without values of losing, if players are heterogenous (they have di¤erent values) the best-of-three all-pay auction is less competitive (the di¤erence between the players?probabilities to win is larger) as well as less productive (the players?total expected e¤ort is smaller) than the one-stage all-pay auction. If players are homogenous, however, the productivity and obviously the competitiveness of the best-of-three all-pay auction and the one-stage all-pay auction are identical. These results hold even if players have values of losing that do not depend on the stage in which the contest is decided. However, the best-of-three all-pay auction with di¤erent values of losing over the contest?s stages may be more productive than the one-stage all-pay auction.

Sequential Two-Prize Contests

We study two-stage all-pay auctions with two identical prizes. In each stage, players compete for one prize. Each player may win either one or two prizes. We analyze the equilibrium strategies where players’ marginal values for the prizes are either declining or incliningMulti-prize contests, All-pay auctions

ALLOCATION OF PRIZES IN CONTESTS WITH PARTICIPATION CONSTRAINTS

We study all-pay contests with an exogenous minimal effort constraint where a player can participate in a contest only if his effort (output) is equal to or higher than the minimal effort constraint. Contestants are privately informed about a parameter (ability) that affects their cost of effort. The designer decides about the size and the number of prizes. We analyze the optimal prize allocation for the contest designer who wishes to maximize either the total effort or the highest effort. It is shown that if the minimal effort constraint is relatively high, the winner-take-all contest in which the contestant with the highest effort wins the entire prize sum does not maximize the expected total effort nor the expected highest effort. In that case, the random contest in which the entire prize sum is equally allocated to all the participants yields a higher expected total effort as well as a higher expected highest effort than the winner-take-all contest.Winner-take-all contests, all-pay auctions, participation constraints.

ROUND-ROBIN TOURNAMENTS WITH EFFORT CONSTRAINTS

We study a round-robin tournament with n symmetric players where in each of the n-1 stages each of the players competes against a different player in the Tullock contest. Each player has a limited budget of effort that decreases within the stages proportionally to the effort he exerted in the previous stages. We show that when the prize for winning (value of winning) is equal between the stages, a player's effort is weakly decreasing over the stages. We also show how the contest designer can influence the players' allocation of effort by changing the distribution of prizes between the stages. In particular, we analyze the distribution of prizes over the stages that balance the effort allocation such that a player exerts the same effort over the different stages. In addition, we analyze the distribution of prizes over the stages that maximizes the players' expected total effort.

The Optimal Allocation of Prizes in Contests

We study a contest with multiple (not necessarily equal) prizes. Contestants have private information about an ability parameter that affects their costs of bidding. The contestant with the highest bid wins the first prize, the contestant with the second-highest bid wins the second prize, and so on until all the prizes are allocated. All contestants incur their respective costs of bidding. The contest's designer maximizes the expected sum of bids. Our main results are: 1) We display bidding equlibria for any number of contestants having linear, convex or concave cost functions, and for any distribution of abilities. 2) If the cost functions are linear or concave, then, no matter what the distribution of abilities is, it is optimal for the designer to allocate the entire prize sum to a single ''first'' prize. 3) We give a necessary and sufficient conditions ensuring that several prizes are optimal if contestants have a convex cost function.

Contest Architecture

A contest architecture specifies how the prize sum is split among several prizes, and how the contestants (who are here privately informed about their abilities) are split among several sub-contests. We compare the performance of such schemes to that of grand winner-take-all contests from the point of view of designers who maximize either the expected total effort or the expected highest effort. An important explanatory variable is the form of the agents` cost functions. The analysis is based on simple but powerful results about various stochastic dominance relations among order statistics and functions thereof.

Sequential All-Pay Auctions with Head Starts and Noisy Outputs

We study a sequential (Stackelberg) all-pay auction with two contestants who are privately informed about a parameter (ability) that affects their cost of effort. Contestant 1 (the fi?rst mover) exerts an effort in the fi?rst period, while contestant 2 (the second mover) observes the effort of contestant 1 and then exerts an effort in the second period. Contestant 2 wins the contest if his effort is larger than or equal to the effort of contestant 1; otherwise, contestant 1 wins. We characterize the unique subgame perfect equilibrium of this sequential all-pay auction and analyze the use of head starts to improve the contestants' performances. We also study this model when contestant 1 exerts an effort in the fi?rst period which translates into an observable output but with some noise. We study two variations of this model where contestant 1 either knows or does not know the realization of the noise before she chooses her effort. Contestant 2 does not know the realization of the noise in both variations. For both variations, we characterize the subgame perfect equilibrium and investigate the effect of a random noise on the contestants' performance.Sequential all-pay auctions, head starts, noisy outputs.

One against all in the fictitious play process

There are only few "positive" results concerning multi-person games with the fictitious play property, that is, games in which every fictitious play process approaches the set of equilibria. In this paper we chararcterize classes of multi-person games with the fictitious play property. We consider an (n+1) player game {0,1,2,...,n} based on n two-person sub-games. In each of these sub-games player 0 plays against one of the other players. Player 0 is regulated, so that he must choose the same strategy in all n sub-games. we show that if all sub-games are either zero-sum ganes, weighted potential games, or games with identical payoff functions, then the fictitious play property holds for the associated game

Fictitious play and- no-cycling conditions

We investigate the paths of pure strategy profiles induced by the fictitious play process. We present rules that such paths must follow. Using these rules we prove that every non-degenerate 2*3 game has the continuous fictitious play property, that is, every continuous fictitious play process, independent of initial actions and beliefs, approaches equilibrium in such games.