Events U and V can be handled in the obvious fashion.
Event W is cause for mild concern, with potential for alarm. Start by assuming the event has high probability (~ 1), and compute an output. The try with low probability (~ 0). If the outputs are the same, ignore the problem and await more evidence. If the outputs are similar, attempt to decide whether the difference between them might plausibly have a large impact. If not, pick something within that range and proceed. If the problem remains unsolved, go into alarm mode and request programmer assistance.
Events X and Y can be mitigated with an appropriate prior for the expected utility of a typical action, as informed by past experience. That should allow for reasonable decisions in many cases of (unreasonable utility) * (unreasonable probability), since those terms will produce a very low expected utility one way or the other. If the problem is still unresolved, seek programmer guidance.
Events U and V can be handled in the obvious fashion.
Event W is cause for mild concern, with potential for alarm. Start by assuming the event has high probability (~ 1), and compute an output. The try with low probability (~ 0). If the outputs are the same, ignore the problem and await more evidence. If the outputs are similar, attempt to decide whether the difference between them might plausibly have a large impact. If not, pick something within that range and proceed. If the problem remains unsolved, go into alarm mode and request programmer assistance.
Events X and Y can be mitigated with an appropriate prior for the expected utility of a typical action, as informed by past experience. That should allow for reasonable decisions in many cases of (unreasonable utility) * (unreasonable probability), since those terms will produce a very low expected utility one way or the other. If the problem is still unresolved, seek programmer guidance.
Event Z can be handled analogously to event W.