1.6 Extended Models 11
be predicted with certainty. The plan is unconditional, and the controller executing
the plan is an open-loop controller, i.e., it does not get any feedback about the state
of the system.
This restricted case may appear trivial: planning is simply searching for a path
in a graph, which is a well-known and well-solved problem. Indeed, if we are given
the graph explicitly then there is not much more to say about planning for this
restricted case. However even for a very simple application domain, the graph
can be so large that specifying it explicitly is not feasible. In the simple example
introduced earlier (Example 1.1), in which a robot has to move containers, suppose
there are five locations, three piles of containers per ...