  An experiment replicated and extended recent findings on psychologically
realistic ways of modeling propagation of uncertainty in rule based reasoning.
Within a single production rule, the antecedent evidence can be summarized by
taking the maximum of disjunctively connected antecedents and the minimum of
conjunctively connected antecedents. The maximum certainty factor attached to
each of the rule's conclusions can be sealed down by multiplication with this
summarized antecedent certainty. Heckerman's modified certainty factor
technique can be used to combine certainties for common conclusions across
production rules.
