There is a very good chance that Bernhard is white. It is improbable that Brian is a rhino. There is a better than even chance that Julius is white. There is little chance that if 'Julius is white' or 'Brian is a rhino' or both then Greg is a swan. It is probably not the case that if 'Bernhard is white' or 'Julius is white' or both then Bill moved to the office. There is almost no chance that if either 'Julius is white' or 'Bernhard is white' but not both then Sandra got the milk.
Chances are about even that either 'Bernhard is white' or 'Julius is white' but not both.
Chances are about even that either 'Bernhard is white' or 'Julius is white' but not both.
There is almost no chance that either 'Bernhard is white' or 'Julius is white' 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
  0.8::factA.
  0.1::factB.
  0.6::factC.
  %hop1
  0.1::factX:-or(factC,factB).
  0.25::factY:-or(factA,factC).
  0.02::factZ:-xor(factC,factA).

  %hop2
  conclusion:-xor(factA,factC).

  query(conclusion).
  
Either 'Bernhard is white' or 'Julius is white' but not both.