CPE/CSC 480-F06 Artificial Intelligence Lab Exercise 4

This lab exercise builds upon the previous ones with the Bot Environment. Your agent needs to systematically explore the environment by employing the depth-first search algorithm.

Search Strategies

In order to perform a systematic search, the two fundamental strategies are breadth-first and depth-first. In addition, the agent needs to select among nodes at the same level in a systematic manner. The most frequently used selections here are left-to-right or right-to-left with respect to the way the nodes are listed in a graphical view. Depending on the type of the nodes, there is also often an obvious ordering, such as alphabetical or numerical.

Depth-First Search Algorithm

In this strategy, the first successor node is selected, then the first successor node of this node, and so on until a leaf node (without successors) is encountered. In this case, the search backtracks to the least recently visited node with an unexplored successor, and continues from there. In the tree, the search goes down one branch until the end is reached, then goes back to the last branching point and continues from there.

Please use the same clockwise ordering as in the previous lab, starting from the "North" position (i.e. in the order North, East, South, West).

Tasks

Your task is to implement an agent for the depth-first search strategy.

Search in the Bot Environment

More information on how to use the environment can be found by following the link to the bot search tutorial. If you have problems with it, post your questions on the "BotEnvironment" Blackboard discussion forum.

Approach

If you used the general search approach, it should be fairly straightforward to modify the breadth-first agent in order to obtain a depth-first agent.

Assignment Submission

This assignment must be submitted electronically via the handin program on hornet by the deadline specified above. You need to submit the following items:

• a plain text file (not a MS Word document) named README.txt with your name, a brief explanation of your program, and instructions for compiling and running your program
• the Java source code for your depth-first agent
• the Java executable (class file) for your agent
• optionally additional files that may be relevant for the grading (e.g. make files, log files, or special environments you used)

Collaboration

This is an individual assignment. You must figure out and formulate your own answers, and write your own programs. It is fine with me to discuss general aspects of this lab with others (e.g. general aspects of the different search strategies, or issues with the use of the BotEnvironment).

Questions about the Assignment

If you have questions or comments concerning the programming aspects of the lab, post them on the "Labs" Blackboard Discussion Forum; general questions about the BotEnvironment (e.g. compilation issues, how to use its classes or methods) should go in the forum we set up for that purpose. We will check Blackboard forum on a regular basis, and try to answer your questions.