It is unlikely that Fred put down the apple. There is almost no chance that Bernhard is a swan. It is probably the case that John dropped the apple. It is highly likely that if 'John dropped the apple' or 'Fred put down the apple' or both then Brian is a swan. It is highly likely that if 'John dropped the apple and Bernhard is a swan' then Lily is white. There is a very good chance that if either 'Bernhard is a swan' or 'John dropped the apple' but not both then Julius is a lion.
It is highly unlikely that 'Fred put down the apple' or 'Julius is a lion' or both.
There is a better than even chance that 'Fred put down the apple' or 'Julius is a lion' or both.
It is highly unlikely that 'Fred put down the apple' or 'Julius is a lion' 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
  0.2::factA.
  0.02::factB.
  0.7::factC.
  %hop1
  0.9::factX:-or(factC,factA).
  0.9::factY:-and(factC,factB).
  0.8::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Fred put down the apple' or 'Julius is a lion' or both.