Abstract
A duel involves two stationary players who shoot at each other until at least one of them dies; a truel is similar but involves three players. In the past, the duel has been studied mainly as a component of the truel, which has received considerably more attention. However we believe that the duel is interesting in itself. In this paper we formulate the duel (with either simultaneous or sequential shooting) as a discounted stochastic game. We show that this game has a unique Nash equilibrium in stationary strategies; however, it also possesses cooperation-promoting Nash equilibria in nonstationary strategies. We show that these are also subgame perfect equilibria. Finally, we argue that the nature of the game and its equilibria is similar to that of the repeated Prisoner’s dilemma.




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Notes
There is no loss of generality in assuming \(a_{1}=1\), because \(\Pi _{1}\left( \delta \right) \) is homogeneous in \(a_{1}\) and \(b_{1}\).
Of course, when the game is in \(\left( 2,1,0\right) \), \(P_{2}\) is supposed to have the shot, but he cannot actually shoot, since he is already dead; similarly for \(\left( 1,0,1\right) \) and \(P_{1}\).
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Kehagias, A. The Duel Discounted Stochastic Game. Dyn Games Appl 14, 846–864 (2024). https://doi.org/10.1007/s13235-023-00540-9
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DOI: https://doi.org/10.1007/s13235-023-00540-9