Towards formal theories of autonomous goal-directed behavior

After many years of focussing on various aspects of the pure motion planning problem (well documented in Latombe's book [3]), the time has come for the path planning community to widen the scope of the planning of goal-directed behavior, and to include the sensory actions. This will connect the work from the motion planning area to the theoretical work in sensing of, for instance, [2]. This special issue brings together some approaches that have been taken in the formal study of goal-directed behavior for autonomous systems. The papers reflect the incompleteness and tentativeness of the results sofar, but also make plausible'that more definite results seem to be within reach. As such, they should be inspiring to many readers. An exciting aspect of the papers is that, though they treat vastly different aspects of autonomous behavior, they are written in a common language: geometry. Fig. 1 is helpful in visualizing the locations and relationships of the different contributions within the