It is highly unlikely that Mary got the apple. It is likely that John dropped the apple. There is a very good chance that Julius is a rhino. Chances are about even that if 'Mary got the apple and Julius is a rhino' then Lily is white. Chances are about even that if either 'Mary got the apple' or 'John dropped the apple' but not both then Emily is a sheep. We doubt that if 'Mary got the apple' or 'John dropped the apple' or both then Greg is gray.
There is almost no chance that 'Lily is white' or 'Julius is a rhino' or both.
There is a very good chance that 'Lily is white' or 'Julius is a rhino' or both.
There is almost no chance that 'Lily is white' 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
  0.05::factA.
  0.7::factB.
  0.8::factC.
  %hop1
  0.5::factX:-and(factA,factC).
  0.5::factY:-xor(factA,factB).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Lily is white' or 'Julius is a rhino' or both.