There is little chance that Daniel got the milk. There is little chance that Jessica is a sheep. There is a very good chance that John went to the garden. It is highly unlikely that if either 'Jessica is a sheep' or 'Daniel got the milk' but not both then Lily is a lion. We doubt that if 'Daniel got the milk' or 'Jessica is a sheep' or both then Brian is green. There is little chance that if 'Daniel got the milk' or 'John went to the garden' or both then Greg is a rhino.
It is probable that either 'Jessica is a sheep' or 'Daniel got the milk' but not both.
It is unlikely that either 'Jessica is a sheep' or 'Daniel got the milk' but not both.
It is probable that either 'Jessica is a sheep' or 'Daniel got the milk' 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.
  0.1::factB.
  0.8::factC.
  %hop1
  0.05::factX:-xor(factB,factA).
  0.2::factY:-or(factA,factB).
  0.1::factZ:-or(factA,factC).

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

  query(conclusion).
  
Either 'Jessica is a sheep' or 'Daniel got the milk' but not both.