AlphaEdgeInternal
yields a possible objective prior distribution for each situation
associated with a particular variable in the event tree.
AlphaEdgeInternal(level, stratified.event.tree, alpha)
numeric - It indicates the level in the event tree.
Stratified.event.tree - S4 object that represents an event tree.
numeric - It plays a role of a phantom sample to construct the prior probability distribution of a situation associated with a particular variable in the event tree.
"vector" - Dirichlet hyperparameter vector of a situation associated with a particular variable.