- INSTANCE:
A simple polygon
*P*and the visibility polygon*V*of the location of a robot inside*P*. - SOLUTION:
A motion scheme for the robot to determine its exact location.
- MEASURE:
The distance the robot travels according to the motion scheme.

*Good News:*Approximable within where*H*is the set of points in*P*with visibility polygon*V*[139].*Comment:*The problem SHORTEST WATCHMAN ROUTE where the polygon*P*have holes and the problem is to find a shortest tour inside*P*such that the robot can see all of*P*is approximable within , where*m*is the minimum number of edges in an optimal rectilinear tour [374].