CS2710 / ISSP 2160: Homework 4

Planning (Chapters 10, 11)

Assigned: October 27, 2009

Due: November 10, 2009

I. Partial Order Planning (10 pts)

Consider the problem of putting on one's shoes and socks, as defined in Section 11.3 of the textbook. We will now add actions for putting on a coat and putting on a hat. Show the partial order plan that is a solution, and explain why there are 180 different linearizations of the partial-order plan.

II. Blackbox: Planning with graphs and SAT (90 pts)

The domain we will define is a simple trucking domain, which has three types of objects: trucks, cities and packages. Trucks are used to transport packages from one city to another. A truck can go directly from any city to any other city with a "drive" operator. Each truck can transport just one package at a time from one city to another. To load a package in a truck, the truck must be empty and the truck and package must both be at the same city. When you unload a package from a truck, it becomes empty again.

A. Problem Formulation (20 pts) (For Report)

1) (10 pts) Define this planning domain in PDDL, using three operators: "drive", "load" and "unload".

2) (10 pts) Let's also consider how you might begin to define this planning problem if you instead were using situation calculus.

(a) What would be the fluents and the eternals in this domain?

(b) What would be a suitable logical description of one of the initial situations you use below?

B. Implementation (70 pts) ((1)-(3) for Program, (4) for Report)

1) (15 pts) Test your domain on a simple problem that requires moving a package from one location to another. Make sure that the package is not in two cities at the same time. Turn in a print out of your domain, initial state, goal state, and trace of a successful run.( Name it "testOutput.txt")

2) (20 pts) Test your domain on problems that require moving 1, 5 and 10 packages from one location to another. Use the statistics reported by Blackbox to see how long the planner takes for each of these problems. What if you also increase the number of cities?

3) (20 pts) Remove the restriction that a truck can only transport one package at a time. How does it affect Blackbox's performance for the different numbers of packages?

4) (15 pts) Turn in a description of the behavior of Blackbox when you increase the number of packages, cities, and trucks (assume no more than 5 trucks).

Hints:

• The language that Blackbox accepts is PDDL. The best way to understand the language is look at the Examples directory in the Blackbox distribution. You can consult a couple of tutorial pages: PDDL examples (from Manuela Veloso), and writing PDDL (from Patrick Doherty).
• To get the Examples directory, you may have to download the source code (i.e., not the binary) distribution of BlackBox. When you unzip the file, you'll see a directory named Examples.
• After you compile the code, you need to copy the binary code "blackbox" to the same directory of the problem that you want to solve.
• To run blackbox use a command such as: ./blackbox -o myDomain.pddl -f myProblemDescriptor.pddl, where myDomain.pddl contains the description of the problem domain (names and argument lists of predicates, as well as constants). The myProblemDescriptor.pddl file defines the particular planning problem that should be solved within the specified domain.
• Follow the advice of the blackbox page and, after downloading the Examples directory, try (from the command line):
  cd Examples/logistics-strips
  ./blackbox -o domain.pddl -f  prob004-log-a.pddl