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Unformatted text preview: CS228 Programming Assignment#1 1 CS 228, Winter 2009 Programming Assignment #1Inference in Graph ical Models In this assignment you will implement the Sum Product Message Passing algorithm for exact inference in Graphical Models, and then extend the algorithm to perform Loopy Belief Propaga tion for approximate inference. All code is to be written in Matlab. If you are unfamiliar with Matlab, you should read one of the excellent Matlab tutorials available on the web (for example, http://www.mathworks.com/academia/student center/tutorials/launchpad.html ). For this assignment, you may work on your own or in a pair. If you need to find a partner, you may post on the course wiki: http://pmai.wikidot.com/matching . The assignment is due at 11:59pm on Thursday Feb. 5 . Submission procedures can be found on the course website at http://www.stanford.edu/class/cs228/submissions.html . The primary network that we will use to test your code is the INSURANCE network (shown in Fig. 1 below). The INSURANCE network is a realworld network that was developed for esti mating the expected claim costs for a car insurance policyholder. There are 27 variables in the network with between two and five values per variable. If you are curious, you can find the original paper that mentioned this network at http://citeseer.ist.psu.edu/binder97adaptive.html . You will be provided with a description of the network that can easily be read into Matlab (see problem 1 below). We also provide a constructed clique tree and cluster graph for the network so that your implementation will simply focus on implementing inference over these structures. Because your code will be general enough to handle other networks, and in order to give a more practical flavor to the power of inference, we also provide a Things and Stuff (TAS) network, which is based on recent research by Geremy Heitz, a PhD student of Prof. Koller. (If youre interested, you can find the paper, examples, and other materials at http://ai.stanford.edu/ gaheitz/Research/TAS/ ). Details on the TAS networks are below. 1. [60 points] Code All code for this assignment should be copied from /afs/ir/class/cs228/ProgrammingAssignments/PA1/assignment. You should be able to access this by logging into the Stanford Unix machines (e.g., cardinal.stanford.edu) using your SUNet ID. You can also use a copy of Matlab on any of the machines that allow CPUintensive jobs (tree, vine, bramble, hedge). Your job is to fill in the missing portions of code marked with YOUR CODE HERE in the files described below. The script TestPA1.m is the main routine that sets up the tests to be run and also evaluates whether your implementation is correct. Initially, running this script without making any code changes should result in all tests failing (though they should run without error)....
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 Winter '09

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