It is improbable that Greg is a frog. It is almost certain that Bernhard is a rhino. It is almost certain that Mary went to the office. Chances are about even that if 'Greg is a frog' or 'Bernhard is a rhino' or both then Sandra left the milk. It is improbable that if either 'Mary went to the office' or 'Greg is a frog' but not both then Jason is tired. We doubt that if 'Mary went to the office and Bernhard is a rhino' then Jessica is a mouse.
It is highly likely that either 'Bernhard is a rhino' or 'Jason is tired' but not both.
It is highly likely that either 'Bernhard is a rhino' or 'Jason is tired' but not both.
There is almost no chance that either 'Bernhard is a rhino' or 'Jason is tired' but not both.

  and(A,B) :- A,B.
  or(A,B) :- A;B.
  nand(A,B) :- not(and(A,B)).
  nor(A,B) :- not(or(A,B)).
  xor(A,B) :- or(A,B), nand(A,B).

  %hop0
  0.1::factA.
  0.95::factB.
  0.95::factC.
  %hop1
  0.5::factX:-or(factA,factB).
  0.1::factY:-xor(factC,factA).
  0.2::factZ:-and(factC,factB).

  %hop2
  conclusion:-xor(factB,factY).

  query(conclusion).
  
Either 'Bernhard is a rhino' or 'Jason is tired' but not both.