It is impossible that Julius is a swan. There is little chance that Mary went to the bedroom. We doubt that Brian is white. Chances are slight that if 'Julius is a swan and Brian is white' then Lily is gray. It is highly likely that if 'Julius is a swan and Mary went to the bedroom' then Jessica is a cat. It is unlikely that if 'Brian is white' or 'Mary went to the bedroom' or both then John dropped the milk.
It is impossible that 'Julius is a swan and Brian is white'.
It is impossible that 'Julius is a swan and Brian is white'.
It is probably the case that 'Julius is a swan and Brian is white'.

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

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

  query(conclusion).
  
'Julius is a swan and Brian is white'.