We believe that Jeff went to the bedroom. It is certain that Daniel dropped the milk. It is probably not the case that Julius is a swan. There is a better than even chance that if 'Julius is a swan' or 'Jeff went to the bedroom' or both then Lily is white. It is almost certain that if either 'Daniel dropped the milk' or 'Jeff went to the bedroom' but not both then Gertrude is a mouse. It is impossible that if either 'Daniel dropped the milk' or 'Julius is a swan' but not both then Brian is a rhino.
It is improbable that 'Julius is a swan' or 'Daniel dropped the milk' or both.
It is certain that 'Julius is a swan' or 'Daniel dropped the milk' or both.
It is improbable that 'Julius is a swan' or 'Daniel dropped 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
  0.75::factA.
  1.0::factB.
  0.25::factC.
  %hop1
  0.6::factX:-or(factC,factA).
  0.95::factY:-xor(factB,factA).
  0.0::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Julius is a swan' or 'Daniel dropped the milk' or both.