next up previous
Next: Multiple Sources of Up: Contingencies Previous: Introducing Contingencies

Uncertainties with Multiple Outcomes

Although the algorithm we have described can deal with uncertainties having any number of possible outcomes, we have so far discussed only examples with two possible outcomes. In fact, two-outcome uncertainties suffice to describe the majority of problems that we have considered. Indeed, technically, any situation could be described in terms of some number of two-outcome uncertainties. However, it is not hard to think of situations that might naturally be represented in terms of a source of uncertainty with more than two outcomes. For example, suppose the planner were interested in getting hold of a particular object in a situation in which the object were known to be in one of three places. In such a case, the start pseudo-operator would naturally be represented as having three uncertain effects (one for each possible location of the object) all associated with alternative outcomes of a single source of uncertainty. Cassandra's plan for acquiring the object would then involve three contingencies, one for each possible location.

Louise Pryor <>;
Last modified: Mon Mar 18 17:11:48 1996