There is almost no chance that Bernhard is a swan. There is almost no chance that John dropped the apple. It is almost certain that Julius is a swan. It is likely that if either 'Julius is a swan' or 'Bernhard is a swan' but not both then Mary went to the office. It is likely that if 'Julius is a swan and Bernhard is a swan' then Greg is yellow. There is little chance that if either 'John dropped the apple' or 'Bernhard is a swan' but not both then Brian is a rhino.
It is almost certain that 'Bernhard is a swan' or 'Julius is a swan' or both.
It is almost certain that 'Bernhard is a swan' or 'Julius is a swan' or both.
There is little chance that 'Bernhard is a swan' or 'Julius is a swan' 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
  0.02::factA.
  0.02::factB.
  0.95::factC.
  %hop1
  0.7::factX:-xor(factC,factA).
  0.7::factY:-and(factC,factA).
  0.1::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Bernhard is a swan' or 'Julius is a swan' or both.