Risk Parameters for Utilitarian Desires ( extended abstract )

In qualitative decision-theoretic planning desires { qualitative abstractions of utility functions { are combined with defaults { qualitative abstractions of probability distributions { to calculate the expected utilities of actions. In this paper we consider Lang's framework of qualitative decision theory, in which utility functions are constructed from desires. Unfortunately there is no consensus about the desired logical properties of desires, in contrast to the case for defaults. To do justice to the wide variety of desires we deene parameterized desires in an extension of Lang's framework. There are three parameters. The strength parameter encodes the importance of the desire, the lifting parameter encodes how to determine the utility of a set from the utilities of its elements, and the polarity parameter encodes the relation between gain of utility for rewards and loss of utility for violations. The parameters innuence how desires interact, and they thus increase the control on the construction process of utility functions from desires.