In order to determine how the source node votes over a QuestionPair edge, we need to calculate some probabilities.
we need to determine the probability that a user will vote for possible answer k in the target question Q I given that she voted for answer l in the source question Q J : where C(Q In , Q J l ) is the number of users who voted for answer n in Q I and answer l in Q J , and A(Q I ) is the set of possible answers on Q I .