For the baseline, “underlying” probability of the oracle’s request being declined. Roughly speaking, if you have never seen X happen, it does not mean that X will never happen (=has a probability of zero).
This assumes you’re a passive observer, by the way—if you are actively making a decision whether to accept or decline the request you can’t apply Bayesian probabilities to your own actions.
That’s a forward-looking probability and is certainly not zero.
In the absence of evidence you just fall back on your prior.
In order to get Error: Divide By Zero, you have to be using a particular kind of decision theory and assume P(decline oracle’s request) = 0.
Your prior for what?
For the baseline, “underlying” probability of the oracle’s request being declined. Roughly speaking, if you have never seen X happen, it does not mean that X will never happen (=has a probability of zero).
This assumes you’re a passive observer, by the way—if you are actively making a decision whether to accept or decline the request you can’t apply Bayesian probabilities to your own actions.