Assigned: November 20, 2008 (by end of day)
Due: December 4, 2008
Consider the following simple domain:
Trace in detail how a partial-order regression planner finds a plan for this problem. This means show the various partial-order plans together with their ordering constraints and causal links.
To get full credit, you should first - in words - describe each step in your plan space search. For example:
In addition, you should create a corresponding diagram representing the partial plan for each state.Here's one suggested notation, similar to that used in class. Use a labelled square to represent an operator. Use letters above the squares for preconditions and letters below for effects. Use single width arrow lines for ordering constraints, and double width arrow lines for causal links. (As discussed in class, not all ordering constraints need to be shown in the graph as causal links are assumed to be accompanied by a similar ordering constraint).
Assume a blocks world with the STRIPS operator Move(x,y,z) defined as follows:
The initial state is
The goal condition is:
(a) Draw the full search tree in a state-space search (assume no repeated states). Give each state a unique number. For full credit, be sure to show the list of predicates (or the equivalent graphical representation of the blocks) for each state, and explicitly label the actions that get you from one state to another (as in Figure 11.5).
(b) Assume you want to use a forward heuristic search to explore this space, using the following evaluation function:
List the states in the order they would be visited, using your numbering from part (a). (Pick randomly in case of ties for f.)