It is shown that the prekernel and the pre-nucleolus of a cooperative game coincide with the kernel and the nucleolus for the reasonable set of the game respectively.

An infiltrator tries to go through a graph of n arcs, within a time limit, without being caught by a guard. The latter is allowed a restricted number of tentatives to catch the infiltrator. This paper describes optimal strategies and gives the value of this discrete zero-sum infiltration game.