How to Make Reactive Planners Risk-Sensitive*

Probabilistic planners can have various planning objectives: usually they either maximize the probability of goal achievement or minimize the expected execution cost of the plan. Researchers have largely ignored the problem how to incorporate risk-sensitive attitudes into their planning mechanisms. We discuss a risk-sensitive planning approach that is based on utility theory. Our key result is that this approach can, at least for risk-seeking attitudes, be implemented with any reactive planner that maximizes (or satisfices) the probability of goal achievement. First, the risk-sensitive planning problem is transformed into a different planning problem, that is then solved by the planner. The larger the probability of goal achievement of the resulting plan, the better its expected utility is for the original (risk-sensitive) planning problem. This approach extends the functionality of reactive planners that maximize the probability of goal achievement, since it allows one to use them (unchanged) for risk-sensitive planning.