It is probably the case that Daniel dropped the apple. There is almost no chance that Lily is green. There is almost no chance that Jessica is a cat. It is unlikely that if either 'Lily is green' or 'Jessica is a cat' but not both then Bernhard is gray. Chances are slight that if 'Daniel dropped the apple and Lily is green' then Julius is a rhino. It is improbable that if either 'Lily is green' or 'Jessica is a cat' but not both then John went to the kitchen.
We believe that 'John went to the kitchen' or 'Julius is a rhino' or both.
It is impossible that 'John went to the kitchen' or 'Julius is a rhino' or both.
We believe that 'John went to the kitchen' or 'Julius is a rhino' 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
  0.7::factA.
  0.02::factB.
  0.02::factC.
  %hop1
  0.2::factX:-xor(factB,factC).
  0.1::factY:-and(factA,factB).
  0.1::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'John went to the kitchen' or 'Julius is a rhino' or both.