n to the universe, the ProbEvidenceAlgorithm takes two optional arguments. The evidence, which defaults to empty, and the denominator, which defaults to 1.
The evidence is a list of specific evidence items associated with references.
When started, the algorithm computes the probability of the named evidence, in addition to the conditions and constraints in the model, divided by the denominator (partition function).
In a typical use case, one might want to compute the probability of the named evidence, takin