It is unlikely that Sandra got the milk. It is unlikely that Winona is a mouse. It is almost certain that Greg is yellow. It is impossible that if either 'Greg is yellow' or 'Winona is a mouse' but not both then Julius is a lion. It is improbable that if either 'Sandra got the milk' or 'Greg is yellow' but not both then Mary went to the bedroom. It is unlikely that if 'Winona is a mouse' or 'Sandra got the milk' or both then Bernhard is a frog.
We believe that either 'Winona is a mouse' or 'Greg is yellow' but not both.
We believe that either 'Winona is a mouse' or 'Greg is yellow' but not both.
There is almost no chance that either 'Winona is a mouse' or 'Greg is yellow' 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
  0.2::factA.
  0.2::factB.
  0.95::factC.
  %hop1
  0.0::factX:-xor(factC,factB).
  0.1::factY:-xor(factA,factC).
  0.2::factZ:-or(factB,factA).

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

  query(conclusion).
  
Either 'Winona is a mouse' or 'Greg is yellow' but not both.