It is almost certain that Brian is a swan. Chances are slight that Greg is a swan. There is almost no chance that Yann is thirsty. It is likely that if 'Brian is a swan and Yann is thirsty' then John dropped the milk. We doubt that if 'Yann is thirsty' or 'Brian is a swan' or both then Mary went to the bedroom. It is unlikely that if either 'Yann is thirsty' or 'Greg is a swan' but not both then Julius is green.
There is almost no chance that 'Julius is green and Brian is a swan'.
There is almost no chance that 'Julius is green and Brian is a swan'.
It is probably the case that 'Julius is green and Brian is a swan'.

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

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

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