As we have mentioned above, and as we shall see later,
not always the evaluation of updating factors can be done
with the help of mathematical formulae like in the box example.
However, we can make use of the virtual bet in this case too,
remembering that a Bayes factor can be considered
as the odds due a single piece of evidence,
provided the two hypotheses are considered otherwise
equally likely (hence, let us remember, the symbol used here
to indicate Bayes factors).