Now showing 1 - 5 of 5
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    Open-loop and feedback Nash equilibria in constrained linear–quadratic dynamic games played over event trees
    (01-09-2019) ;
    Zaccour, Georges
    We characterize open-loop and feedback Nash equilibria for a class of constrained linear–quadratic multistage games having the following features: (a) The control variables are of two types, namely, control variables that enter the dynamics, but are not constrained, and control variables that are part of state-control constraints, but do not enter the dynamics; (b) The parameter values are uncertain, with the stochastic process being described by a event tree. This paper takes stock on Reddy and Zaccour (2015, 2017) where the same class of games was considered, but in a deterministic setting. Here, we follow the same approaches and rewrite the results in these two papers in a stochastic setting.
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    Sampled-Data Nash Equilibria in Differential Games with Impulse Controls
    (01-09-2021)
    Sadana, Utsav
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    BaÅŸar, Tamer
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    Zaccour, Georges
    We study a class of deterministic two-player nonzero-sum differential games where one player uses piecewise-continuous controls to affect the continuously evolving state, while the other player uses impulse controls at certain discrete instants of time to shift the state from one level to another. The state measurements are made at some given instants of time, and players determine their strategies using the last measured state value. We provide necessary and sufficient conditions for the existence of sampled-data Nash equilibrium for a general class of differential games with impulse controls. We specialize our results to a scalar linear-quadratic differential game and show that the equilibrium impulse timing can be obtained by determining a fixed point of a Riccati-like system of differential equations with jumps coupled with a system of nonlinear equality constraints. By reformulating the problem as a constrained nonlinear optimization problem, we compute the equilibrium timing, and level of impulses. We find that the equilibrium piecewise continuous control and impulse control are linear functions of the last measured state value. Using a numerical example, we illustrate our results.
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    Feedback Nash Equilibria in Differential Games with Impulse Control
    (01-08-2023)
    Sadana, Utsav
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    Zaccour, Georges
    In this article, we study a class of deterministic finite-horizon two-player nonzero-sum differential games where players are endowed with different kinds of controls. We assume that Player 1 uses piecewise-continuous controls, whereas Player 2 uses impulse controls. For this class of games, we seek to derive conditions for the existence of feedback Nash equilibrium strategies for the players. More specifically, we provide a verification theorem for identifying such equilibrium strategies, using the Hamilton-Jacobi-Bellman equations for Player 1 and the quasi-variational inequalities for Player 2. Furthermore, we show that the equilibrium number of interventions by Player 2 is upper bounded. Furthermore, we specialize the obtained results in a scalar two-player linear-quadratic differential game. In this game, Player 1's objective is to drive the state variable toward a specific target value, and Player 2 has a similar objective with a different target value. We provide, for the first time, an analytical characterization of the feedback Nash equilibrium in a linear-quadratic differential game with impulse control. We illustrate our results using numerical experiments.
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    Publication
    Nash equilibria in nonzero-sum differential games with impulse control
    (01-12-2021)
    Sadana, Utsav
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    Zaccour, Georges
    In this paper, we introduce a class of deterministic finite-horizon two-player nonzero-sum differential games where one player uses ordinary controls while the other player uses impulse controls. We use the word ‘ordinary’ to mean that Player 1 uses control strategies that are piecewise continuous functions of time. We formulate the necessary and sufficient conditions for the existence of an open-loop Nash equilibrium for this class of differential games. We specialize these results to linear-quadratic games, and show that the open-loop Nash equilibrium strategies can be computed by solving a constrained non-linear optimization problem. In particular, for the impulse player, the equilibrium timing and level of impulses can be obtained. Furthermore, for the special case of linear-state differential games, we obtain analytical characterization of equilibrium number, timing, and the level of impulse in terms of the problem data. We illustrate our results using numerical experiments.
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    Endogenous Duration of Long-term Agreements in Cooperative Dynamic Games with Nontransferable Utility
    (01-12-2022)
    Parilina, Elena M.
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    Zaccour, Georges
    In this paper, we study the time consistency of cooperative agreements in dynamic games with non-transferable utility. An agreement designed at the outset of a game is time-consistent (or sustainable) if it remains in place for the entire duration of the game, that is, if the players would not benefit from switching to their non-cooperative strategies. The literature has highlighted that, since side payments are not allowed, the design of such an agreement is very challenging. To address this issue, we introduce different notions for the temporal stability of an agreement and determine endogenously the duration of the agreement. We illustrate our general results with a linear-quadratic difference game and show that an agreement’s duration can be easily assessed using the problem data. We also study the effect of information structure on the endogenous duration of the agreement. We illustrate our results with a numerical example.