Object and observer: A surveillance problem

The property of the visibility of an object for an observer is studied in the case when the motion takes place in a space with a fixed bodily set impeding the visibility. Directional derivatives of the visibility function are calculated. The problem of tracking the object by the observer is considered, when the object aims to minimize and the observer aims to maximize the maximum of the visibility function. An algorithm for constructing a trajectory that is best for the object is given for the case when the observer acts optimally.