Chances are slight that Julius is white. It is probable that Emily is a sheep. There is almost no chance that Greg is a frog. There is a very good chance that if 'Greg is a frog' or 'Julius is white' or both then Bernhard is green. There is a better than even chance that if 'Greg is a frog and Emily is a sheep' then Fred moved to the office. There is almost no chance that if 'Greg is a frog' or 'Julius is white' or both then John went to the bedroom.
We doubt that either 'Bernhard is green' or 'Emily is a sheep' but not both.
It is probable that either 'Bernhard is green' or 'Emily is a sheep' but not both.
We doubt that either 'Bernhard is green' or 'Emily is a sheep' 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.
  0.7::factB.
  0.02::factC.
  %hop1
  0.8::factX:-or(factC,factA).
  0.6::factY:-and(factC,factB).
  0.02::factZ:-or(factC,factA).

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

  query(conclusion).
  
Either 'Bernhard is green' or 'Emily is a sheep' but not both.