A Duel Involving False Targets

Abstract

A duel is initated by an attacker at some time t in [− T , 0]. The defender possesses weapons at − T and encounters “false” targets that occur at time t with probability density λ( t ) and are classified as “real” with probability c fa . At the time of attack, the probabilities that the attacker is detected and classified as real are D and c aa ( D , c aa , c fa are constant). If the defender responds with one of his k weapons at the time of attack, he survives with probability p k , and, if he does not respond, he survives with probability q k ; q k < p k , p k ≦ p k +1 , q k ≦ q k +1 for k = 0, 1, 2, …. The payoff is the defender's survival probability. Both players are informed of the current time, the defender's weapon level, λ, D , c aa , C fa , p k and q k ( k = 0, 1, 2, …). The attacker selects a time of attack to minimize the payoff. He may change the attack time as the defender expends weapons against false targets. The defender responds to classifications so as to maximize the payoff. This paper derives an iterative system of first-order differential equations whose unique solution V 1 ( t ), V 2 ( t ), …, V k ( t ), … at time t is the value of the game when the defender has 1, 2, …, k , … weapons, respectively, at time t . It expresses the optimal strategies in terms of the values, and determines the limit of V k ( t ) as k → ∞ with k / ∫ t 0 λ( s ) ds held constant.