On a dynamic fractional game

Consider a two-person zero-sum game constructed by a dynamic fractional form. We establish the upper value as well as the lower value of a dynamic fractional game, and prove that the dual gap is equal to zero under certain conditions. It is also established that the saddle point function exists in the fractional game system under certain conditions so that the equilibrium point exists in this game system.     

Two-target pursuit-evasion differential games in the plane

Two-target versions of the game of two cars and the homicidal chauffeur game are introduced. This enables us to consider pursuitevasion withouta priori role assignment. A generic example of the two-target homicidal chauffeur game is considered in detail; in particular, a map of the game and its corresponding winning strategies are found using Lyapunov methods of analysis. The effects of altering game parameters, such as the speed and maneuverability ratios, and the weapon system parameters are then presented. It is found that certain winning strategies include a swerve-type maneuver and that, for certain sets of parameters, regions of stagnation and different modes of draw occur.This work was partially supported by a grant from Control Data.     

半马尔可夫对策

本文考虑半马尔可夫随机对策.在一定条件下,我们证明随机对策有值函数,两个局中人相对于折扣报酬都有最优策略.     

Feedback Solution of a Class of Differential Games with Endogenous Horizons

In this paper, we consider a class of differential games in which the game ends when a subset of its state variables reaches a certain target at the terminal time. A special feature of the game is that its horizon is not fixed at the outset, but is determined endogenously by the actions of the players; conditions characterizing a feedback Nash equilibrium (FNE) solution of the game are derived for the first time. Extensions and illustrations of the derivation of FNE solutions of the game are provided.     

Chip-Firing and the Critical Group of a Graph

A variant of the chip-firing game on a graph is defined. It is shown that the set of configurations that are stable and recurrent for this game can be given the structure of an abelian group, and that the order of the group is equal to the tree number of the graph. In certain cases the game can be used to illuminate the structure of the group.     

一种资源投入不确定情形下的合作博弈形式及收益分配策略

首先,将经典合作博弈进行扩展,提出了一类模糊联盟合作博弈的通用形式,涵盖常见三种模糊联盟合作博弈,即多线性扩展博弈、比例模糊博弈与Choquet积分模糊博弈.比例模糊博弈、Choquet积分模糊博弈的Shapley值均可以作为一种特定形式下模糊联盟合作博弈的收益分配策略,但是对于多线性扩展博弈的Shapley值一直关注较少,因此利用经典Shapley值构造出多线性扩展博弈的Shapley值,以此作为一种收益分配策略.最后,通过实例分析了常见三类模糊联盟合作博弈的形式及其对应的分配策略,分析收益最大的模糊联盟合作对策形式及最优分配策略,为不确定情形下的合作问题提供了一定的收益分配依据.     

Effort Games and the Price of Myopia

We consider Effort Games, a game‐theoretic model of cooperation in open environments, which is a variant of the principal‐agent problem from economic theory. In our multiagent domain, a common project depends on various tasks; carrying out certain subsets of the tasks completes the project successfully, while carrying out other subsets does not. The probability of carrying out a task is higher when the agent in charge of it exerts effort, at a certain cost for that agent. A central authority, called the principal, attempts to incentivize agents to exert effort, but can only reward agents based on the success of the entire project. We model this domain as a normal form game, where the payoffs for each strategy profile are defined based on the different probabilities of carrying out each task and on the boolean function that defines which task subsets complete the project, and which do not. We view this boolean function as a simple coalitional game, and call this game the underlying coalitional game. We suggest the Price of Myopia (PoM) as a measure of the influence the model of rationality has on the minimal payments the principal has to make in order to motivate the agents in such a domain to exert effort. We consider the computational complexity of testing whether exerting effort is a dominant strategy for an agent, and of finding a reward strategy for this domain, using either a dominant strategy equilibrium or using iterated elimination of dominated strategies. We show these problems are generally #P‐hard, and that they are at least as computationally hard as calculating the Banzhaf power index in the underlying coalitional game. We also show that in a certain restricted domain, where the underlying coalitional game is a weighted voting game with certain properties, it is possible to solve all of the above problems in polynomial time. We give bounds on PoM in weighted voting effort games, and provide simulation results regarding PoM in another restricted class of effort games, namely effort games played over Series‐Parallel Graphs (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On 1-convexity and nucleolus of co-insurance games

The insurance situation in which an enormous risk is insured by a number of insurance companies is modeled through a cooperative TU game, the so-called co-insurance game, first introduced in Fragnelli and Marina (2004). In this paper we present certain conditions on the parameters of the model that guarantee the 1-convexity property of co-insurance games which in turn ensures the nonemptiness of the core and the linearity of the nucleolus as a function of the variable premium. Further we reveal conditions when a co-insurance game is representable in the form of a veto-removed game and present an efficient final algorithm for computing the nucleolus of a veto-removed game.     

Stationary,completely mixed and symmetric optimal and equilibrium strategies in stochastic games

In this paper, we address various types of two-person stochastic games—both zero-sum and nonzero-sum, discounted and undiscounted. In particular, we address different aspects of stochastic games, namely: (1) When is a two-person stochastic game completely mixed? (2) Can we identify classes of undiscounted zero-sum stochastic games that have stationary optimal strategies? (3) When does a two-person stochastic game possess symmetric optimal/equilibrium strategies? Firstly, we provide some necessary and some sufficient conditions under which certain classes of discounted and undiscounted stochastic games are completely mixed. In particular, we show that, if a discounted zero-sum switching control stochastic game with symmetric payoff matrices has a completely mixed stationary optimal strategy, then the stochastic game is completely mixed if and only if the matrix games restricted to states are all completely mixed. Secondly, we identify certain classes of undiscounted zero-sum stochastic games that have stationary optima under specific conditions for individual payoff matrices and transition probabilities. Thirdly, we provide sufficient conditions for discounted as well as certain classes of undiscounted stochastic games to have symmetric optimal/equilibrium strategies—namely, transitions are symmetric and the payoff matrices of one player are the transpose of those of the other. We also provide a sufficient condition for the stochastic game to have a symmetric pure strategy equilibrium. We also provide examples to show the sharpness of our results.     

Continuous-time zero-sum stochastic game with stopping and control

We consider a zero-sum stochastic game for continuous-time Markov chain with countable state space and unbounded transition and pay-off rates. The additional feature of the game is that the controllers together with taking actions are also allowed to stop the process. Under suitable hypothesis we show that the game has a value and it is the unique solution of certain dynamic programming inequalities with bilateral constraints. In the process we also prescribe a saddle point equilibrium.     

基于再保险人分担理赔费用的保险欺诈博弈模型分析

本文首先建立了基于再保险人分担理赔费用的夸大风险损失的索赔欺诈博弈模型，然后分析了保险双方的博弈策略选择及其可能达到的均衡。研究表明，博弈模型存在某种形式的精炼贝叶斯纳什均衡，但如实告知一般不是保单持有人的精炼贝叶斯纳什均衡策略。而且，博弈模型不存在分离均衡，当费用自负率在一定范围内变化时，局中人将交替选用分离策略与合并策略。     

Balancedness of infrastructure cost games

In this paper we study the class of infrastructure cost games. A game in this class models the infrastructure costs (both building and maintenance) produced when a set of users of different types makes use of a certain infrastructure, which may consist of several facilities. Special attention is paid to one facility infrastructure cost games. Such games are modeled as the sum of an airport game and a maintenance cost game. It turns out that the core and nucleolus of these games are very closely related to the core and nucleolus of an associated generalized airport game. Furthermore we provide necessary and sufficient conditions under which an infrastructure cost game is balanced.     

Cores of convex games

The core of ann-person game is the set of feasible outcomes that cannot be improved upon by any coalition of players. A convex game is defined as one that is based on a convex set function. In this paper it is shown that the core of a convex game is not empty and that it has an especially regular structure. It is further shown that certain other cooperative solution concepts are related in a simple way to the core: The value of a convex game is the center of gravity of the extreme points of the core, and the von Neumann-Morgenstern stable set solution of a convex game is unique and coincides with the core.     

Accumulation Games,Part 1: Noisy Search

In an accumulation game, a hider places objects at locations, and a seeker examines these locations. If the seeker discovers an object, the seeker confiscates it. The goal of the hider is to accumulate a certain number of objects before a given time, and the goal of the seeker is to prevent this. In this paper, we first classify various possible variations on the accumulation game. Next, we discuss the so-called noisy accumulation game in which the hider can observe each action of the seeker. We present the solution of this game for all but some marginal cases and illustrate it with computational examples.     

Selective sums of loopy partizan graph games

A loopy partizan graph game is a two-person game of perfect information which is played on a labelled digraph. The disjunctive sum, the continued conjunctive sum, and the selective sum are formulations for playing several l.p.g.g.'s simultaneously, so as to form a single compound game. In this paper, we present an analysis of the selective sum by utilizing certain elements of the theories for the disjunctive sum and the continued conjunctive sum.     

Differential Games of Mixed Type with Control and Stopping Times

We study a zero sum differential game of mixed type where each player uses both control and stopping times. Under certain conditions we show that the value function for this problem exists and is the unique viscosity solution of the corresponding variational inequalities. We also show the existence of saddle point equilibrium for a special case of differential game.      

An axiomatic approach to egalitarianism in TU-games

A core concept is a solution concept on the class of balanced games that exclusively selects core allocations. We show that every continuous core concept that satisfies both the equal treatment property and a new property called independence of irrelevant core allocations (IIC) necessarily selects egalitarian allocations. IIC requires that, if the core concept selects a certain core allocation for a given game, and this allocation is still a core allocation for a new game with a core that is contained in the core of the first game, then the core concept also chooses this allocation as the solution to the new game. When we replace the continuity requirement by a weak version of additivity we obtain an axiomatization of the egalitarian solution concept that assigns to each balanced game the core allocation minimizing the Euclidean distance to the equal share allocation.     

Three person baccarat

Baccarat and the closely related game Chemin-de-Fer are played for high stakes in casinos around the world. Optimal strategies for the player and the banker in the two person game have been developed by Kemeny and Snell. Similar strategies are now the rules of play in Nevada. Thorp and Walden developed card counting strategies to make certain side bets profitable but these bets are no longer allowed. Hence, the game is essentially a Bernoulli trial with a banker edge of 1.24%. For the three person game we determine the banker's strategy that optimally counters the two players fixed rules of play. It is optimal for the players to collude and place indentical bets in which case the game becomes a Bernoulli trial with banker's edge of 0.82%.     

Some projection-like methods for the generalized Nash equilibria

A generalized Nash game is an m-person noncooperative game in which each player’s strategy depends on the rivals’ strategies. Based on a quasi-variational inequality formulation for the generalized Nash game, we present two projection-like methods for solving the generalized Nash equilibria in this paper. It is shown that under certain assumptions, these methods are globally convergent. Preliminary computational experience is also reported.     

Distributionally robust chance-constrained games: existence and characterization of Nash equilibrium

We consider an n-player finite strategic game. The payoff vector of each player is a random vector whose distribution is not completely known. We assume that the distribution of a random payoff vector of each player belongs to a distributional uncertainty set. We define a distributionally robust chance-constrained game using worst-case chance constraint. We consider two types of distributional uncertainty sets. We show the existence of a mixed strategy Nash equilibrium of a distributionally robust chance-constrained game corresponding to both types of distributional uncertainty sets. For each case, we show a one-to-one correspondence between a Nash equilibrium of a game and a global maximum of a certain mathematical program.