We doubt that Bernhard is white. It is almost certain that Brian is green. There is a better than even chance that Julius is a frog. It is unlikely that if 'Bernhard is white' or 'Brian is green' or both then Fred went to the garden. It is highly likely that if 'Brian is green' or 'Julius is a frog' or both then Jessica is a cat. It is impossible that if 'Brian is green' or 'Julius is a frog' or both then John dropped the apple.
There is a better than even chance that 'John dropped the apple' or 'Julius is a frog' or both.
There is a better than even chance that 'John dropped the apple' or 'Julius is a frog' or both.
There is almost no chance that 'John dropped the apple' or 'Julius is a frog' 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.
  0.95::factB.
  0.6::factC.
  %hop1
  0.2::factX:-or(factA,factB).
  0.9::factY:-or(factB,factC).
  0.0::factZ:-or(factB,factC).

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

  query(conclusion).
  
'John dropped the apple' or 'Julius is a frog' or both.