It is improbable that Greg is a frog. It is highly likely that John went to the garden. It is highly unlikely that Julius is a swan. It is probably the case that if 'Julius is a swan and John went to the garden' then Bernhard is a lion. There is almost no chance that if either 'John went to the garden' or 'Julius is a swan' but not both then Yann is bored. It is improbable that if either 'Julius is a swan' or 'Greg is a frog' but not both then Sandra grabbed the milk.
It is certain that either 'Sandra grabbed the milk' or 'Julius is a swan' but not both.
It is highly unlikely that either 'Sandra grabbed the milk' or 'Julius is a swan' but not both.
It is certain that either 'Sandra grabbed the milk' or 'Julius 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
  0.1::factA.
  0.9::factB.
  0.05::factC.
  %hop1
  0.7::factX:-and(factC,factB).
  0.02::factY:-xor(factB,factC).
  0.1::factZ:-xor(factC,factA).

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

  query(conclusion).
  
Either 'Sandra grabbed the milk' or 'Julius is a swan' but not both.