Chances are about even that Greg is a rhino. There is a better than even chance that Mary discarded the milk. It is unlikely that Julius is white. It is highly unlikely that if either 'Julius is white' or 'Greg is a rhino' but not both then Lily is a swan. It is unlikely that if either 'Greg is a rhino' or 'Mary discarded the milk' but not both then Jeff went to the garden. It is impossible that if either 'Mary discarded the milk' or 'Greg is a rhino' but not both then Bernhard is green.
It is likely that either 'Bernhard is green' or 'Lily is a swan' but not both.
There is almost no chance that either 'Bernhard is green' or 'Lily is a swan' but not both.
It is likely that either 'Bernhard is green' or 'Lily is a swan' 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
  0.5::factA.
  0.6::factB.
  0.2::factC.
  %hop1
  0.05::factX:-xor(factC,factA).
  0.2::factY:-xor(factA,factB).
  0.0::factZ:-xor(factB,factA).

  %hop2
  conclusion:-xor(factZ,factX).

  query(conclusion).
  
Either 'Bernhard is green' or 'Lily is a swan' but not both.