Generalization of the main equation of differential game theory

We consider feedback, two-person, zero-sum differential games. We obtain two inequalities for the directional derivatives of the nonsmooth value function. We show that these inequalities, together with the boundary conditions, constitute necessary and sufficient conditions which the value function must satisfy. In the region where the value function is differentiable, the inequalities become the well-known main equation of differential game theory (Isaacs-Bellman equation). The results obtained here may be useful in the approximation of the value function by piecewise smooth splines and also in the classification of singular surfaces.The author would like to thank Academician N. N. Krasovskii for his valuable advice and encouragement.     

Two-dimensional pursuit-evasion game with penalty on turning rates

An approach, both analytical and numerical, is used to solve a two-dimensional pursuit-evasion game characterized by a difficulty level intermediate between that of thesimple motion game (with freely and instantaneously oriented velocities) and that of thegame of two cars (with lower bounds on curvature radii). Each player's velocity has a constant modulus. The maneuvers are penalized by introducing, in the performance index, an integral term for the squared velocity turning rate.The local problem solution is relatively easy to find: the equations of motion and the adjoint equations can be integrated by means of elliptic functions and integrals. The global problem is more delicate to solve, because of the existence of a dispersal singular surface requiring an important numerical search to be determined. Thesynthesis problem (how to express the optimal strategies as functions of state) is not explicitly solvable, but a numerical approach using successive approximations can be developed. Illustrative interception trajectories are given.The authors are grateful to Mr. J. P. Peltier, Head, Guidance Group, Aerospace Mechanics Division, Systems Department, ONERA, Châtillon, France, for his suggestions and his efficient assistance in the numerical aspect of this study.     

A dynamic solution concept for abstract games

Several solution concepts have been defined for abstract games. Some of these are the core, due to Gillies and Shapley, the Von Neumann-Morgenstern stable sets, and the subsolutions due to Roth. These solution concepts are rather static in nature. In this paper, we propose a new solution concept for abstract games, called the dynamic solution, that reflects the dynamic aspects of negotiation among the players. Some properties of the dynamic solution are studied. Also, the dynamic solution of abstract games arising fromn-person cooperative games in characteristic function form is investigated.This research was supported by the Office of Naval Research under Contract No. N00014-75-C-0678, by the National Science Foundation under Grants Nos. MPS-75-02024 and MCS-77-03984 at Cornell University, by the United States Army under Contract No. DAAG-29-75-C-0024, and by the National Science Foundation under Grant No. MCS-75-17385-A01 at the University of Wisconsin. The author is grateful to Professor W. F. Lucas under whose guidance the research was conducted.     

Complex differential games of pursuit-evasion type with state constraints,part 1: Necessary conditions for optimal open-loop strategies

Complex pursuit-evasion games with state variable inequality constraints are investigated. Necessary conditions of the first and the second order for optimal trajectories are developed, which enable the calculation of optimal open-loop strategies. The necessary conditions on singular surfaces induced by state constraints and non-smooth data are discussed in detail. These conditions lead to multi-point boundary-value problems which can be solved very efficiently and very accurately by the multiple shooting method. A realistically modelled pursuit-evasion problem for one air-to-air missile versus one high performance aircraft in a vertical plane serves as an example. For this pursuit-evasion game, the barrier surface is investigated, which determines the firing range of the missile. The numerical method for solving this problem and extensive numerical results will be presented and discussed in Part 2 of this paper; see Ref. 1.This paper is dedicated to the memory of Professor John V. Breakwell.The authors would like to express their sincere and grateful appreciation to Professors R. Bulirsch and K. H. Well for their encouraging interest in this work.     

篮球比赛中的防守假动作

随着篮球运动防守战术的发展,要求运动员在比赛中个人防守更具实效性和针对性。防守中假动作的运用丰富了个人防守技术动作,提高了个人防守能力,从而赢得了比赛的主动。     

Singular differential game numerical techniques

This paper develops a numerical technique to solve a class of zero-sum differential games with singular control. By using this technique and the application of inverse systems, a near-optimal closed-loop technique is developed to generate a numerical solution to this class of problems.     

OPTIMAL RECOVERY OF A SHARED RESOURCE STOCK: A DIFFERENTIAL GAME MODEL WITH EFFICIENT MEMORY EQUILIBRIA

We consider an optimal two-country management of depleted transboundary renewable resources. The management problem is modelled as a differential game, in which memory strategies are used. The countries negotiate an agreement among Pareto efficient harvesting programs. They monitor the evolution of the agreement, and they memorize deviations from the agreement in the past. If the agreement is observed by the countries, they continue cooperation. If one of the countries breaches the contract, then both countries continue in a noncooperative management mode for the rest of the game. This noncooperative option is called a threat policy. The credibility of the threats is guaranteed by their equilibrium property. Transfer or side payments are studied as a particular cooperative management program. Transfer payments allow one country to buy out the other from the fishery for the purpose of eliminating the inefficiency caused by the joint access to the resources. It is shown that efficient equilibria can be reached in a class of resource management games, which allow the use of memory strategies. In particular, continuous time transfer payments (e.g., a share of the harvest) should be used instead of a once-and-for-all transfer payment.     

Stabilization through taxation inn-person games

In formulating solutions forn-person cooperative games, the concept of stability has played a dominant role. Although the core concept has the strongest stability, the core of a game is often empty. In this paper, the taxation system is incorporated into our framework, so that a modified solution concept, which enjoys the stability of core, can be developed. Various formulations based on principles such astaxation proportional to income andequity after tax are given.     

Existence of stationary equilibrium strategies in non-zero sum discounted stochastic games with uncountable state space and state-independent transitions

Non-zero sum discounted stochastic games with uncountable state space and state in-dependent transitions have stationary equilibrium strategies.     

Optimal threat strategies in collective bargaining

A model of collective bargaining in differential games, similar to one considered by Leitmann (Ref. 1), is proposed. Optimal threat strategies are then found and compared with Leitmann's solution. Nash-optimal threat strategies are also found and compared with the other two solutions.The author would like to thank Professor G. Leitmann of the University of California for bringing the author's attention to this subject.