Kutat6: An Entropy-Driven System for Construction of Probabilistic Expert Systems from Databases

Kutat61 is a system that takes as input a database of cases and produces a belief net­ work that captures many of the dependence relations represented by those data. This system incorporates a module for determining the entropy of a belief network and a module for constructing belief networks based on entropy calculations. Kutat6 constructs an initial belief network in which all variables in the database are assumed to be marginally independent. The entropy of this belief net­ work is calculated, and that arc is added that minimizes the entropy of the resulting belief network. Conditional probabilities for an arc are obtained directly from the data­ base. This process continues until an entropy­ based threshold is reached. We have tested the system by generating databases from net­ works using the probabilistic logic-sampling method, and then using those databases as input to Kutat6. The system consistently reproduces the original belief networks with high fidelity.