There is almost no chance that Daniel left the milk. It is probable that Sandra got the milk. We doubt that Greg is a swan. There is a better than even chance that if 'Greg is a swan and Daniel left the milk' then Julius is a rhino. It is probably not the case that if either 'Sandra got the milk' or 'Greg is a swan' but not both then Brian is a swan. We doubt that if either 'Greg is a swan' or 'Sandra got the milk' but not both then John went to the hallway.
It is probable that 'Greg is a swan' or 'Daniel left the milk' or both.
It is unlikely that 'Greg is a swan' or 'Daniel left the milk' or both.
It is probable that 'Greg is a swan' or 'Daniel left the milk' or 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
  0.02::factA.
  0.7::factB.
  0.2::factC.
  %hop1
  0.6::factX:-and(factC,factA).
  0.25::factY:-xor(factB,factC).
  0.2::factZ:-xor(factC,factB).

  %hop2
  conclusion:-or(factC,factA).

  query(conclusion).
  
'Greg is a swan' or 'Daniel left the milk' or both.