We believe that Brian is a swan. It is impossible that Daniel got the milk. It is unlikely that John went to the garden. There is almost no chance that if 'Brian is a swan' or 'Daniel got the milk' or both then Emily is a wolf. It is improbable that if 'Brian is a swan and John went to the garden' then Bernhard is a lion. It is almost certain that if 'Brian is a swan and John went to the garden' then Mary moved to the office.
There is a better than even chance that 'Brian is a swan and Daniel got the milk'.
It is impossible that 'Brian is a swan and Daniel got the milk'.
There is a better than even chance that 'Brian is a swan and Daniel got the milk'.

  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.
  0.0::factB.
  0.2::factC.
  %hop1
  0.02::factX:-or(factA,factB).
  0.1::factY:-and(factA,factC).
  0.95::factZ:-and(factA,factC).

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

  query(conclusion).
  
'Brian is a swan and Daniel got the milk'.