We believe that Julius is a swan. It is almost certain that John grabbed the apple. We believe that Brian is green. We doubt that if either 'Julius is a swan' or 'John grabbed the apple' but not both then Bernhard is white. It is certain that if either 'Julius is a swan' or 'Brian is green' but not both then Mary went to the bedroom. It is almost certain that if 'Julius is a swan' or 'Brian is green' or both then Greg is a frog.
It is probable that 'Julius is a swan and John grabbed the apple'.
It is probable that 'Julius is a swan and John grabbed the apple'.
It is highly unlikely that 'Julius is a swan and John grabbed the apple'.

  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.
  0.95::factB.
  0.75::factC.
  %hop1
  0.2::factX:-xor(factA,factB).
  1.0::factY:-xor(factA,factC).
  0.95::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Julius is a swan and John grabbed the apple'.