It is highly unlikely that Lily is white. There is almost no chance that Winona is a sheep. There is a very good chance that John discarded the milk. It is certain that if 'John discarded the milk' or 'Lily is white' or both then Brian is a swan. It is probably not the case that if either 'Winona is a sheep' or 'John discarded the milk' but not both then Gertrude is a mouse. We believe that if 'Winona is a sheep' or 'Lily is white' or both then Bill went to the garden.
There is a very good chance that 'Brian is a swan' or 'John discarded the milk' or both.
There is a very good chance that 'Brian is a swan' or 'John discarded the milk' or both.
We doubt that 'Brian is a swan' or 'John discarded 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
  0.05::factA.
  0.02::factB.
  0.8::factC.
  %hop1
  1.0::factX:-or(factC,factA).
  0.25::factY:-xor(factB,factC).
  0.75::factZ:-or(factB,factA).

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

  query(conclusion).
  
'Brian is a swan' or 'John discarded the milk' or both.