BN

Content-Type: text/html; charset="us-ascii" Content-Disposition: attachment; filename="website.html" BN Brief Introduction to Belief Network(draft)
(Prepared for Use in cosc 6368)

Link for a brief introductory background material on statistics/probability.

For a brief introudctory background material on bayesian statistics try the following links.

1 2 3 4 5

For lecture slides on baysian statistics/networks try:

Russell
Koller

For various Software Tools on Belief Networks try:

KDD
ALMOND

On the basis of a preliminary survey that we (the black group) have done in accordance with the requirements of the course assignment, we have selected, downloaded, and tested two of the software tools. Namely, Hugin and Netica for PC and NT platforms (although we have manage to download a Unix version of Hugin, we have experienced some difficulty in running the software on the machine at the Lab. We have not come across a free Unix version of Netica to download - although they have a commercial solaris version).

To Download Hugin try: http://www.hugin.dk/demo/
To Download Netica try: http://www.norsys.com/download.html

Introductory manual for Hugin may be obtained from: http://www.hugin.dk/hugintro/
Introductory manual for Nettica may be obtained from: http://www.norsys.com/download.html

Below are sample outputs from the examples we have used to test (create and maintain Belief Network) both softwares. Also look at http://www.agena.co.uk/bbn_article/bbns.html for another exmaple on Hugin.

The general procedure to be followed in creating and maintaining Belief Network in both of the
software seems pretty simple and is as follows:

create Nodes for each variable;
add node properties such as name, label, status(possible variable values);
link the nodes;
enter probabilities into tables in respect of each node (note the difference between unconditional and conditional probabilities as you enter the number);
compile the network

Once these steps are done, you can enter evidence/observation, and then Run/Sum to see the effect on others.

Here are samples of nodes, links, and tables that we have created as part of the testing. Please note also that, we have tested both softwares on PC, and NT for the example reported in Hugin tutorial, although not reported in here. In all the cases, the results obtained from both sofewares were identical.

If you have questions or comments, please contact tesfaye@pegasus.cs.uh.edu, or afu@pegasus.cs.uh.edu

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