It is certain that Sandra left the apple. There is almost no chance that Greg is a rhino. It is certain that Brian is green. We doubt that if 'Brian is green and Sandra left the apple' then Lily is white. There is a better than even chance that if 'Sandra left the apple' or 'Brian is green' or both then Sumit is tired. It is highly unlikely that if 'Sandra left the apple' or 'Greg is a rhino' or both then Bernhard is a swan.
It is improbable that 'Bernhard is a swan' or 'Brian is green' or both.
It is certain that 'Bernhard is a swan' or 'Brian is green' or both.
It is improbable that 'Bernhard is a swan' or 'Brian is green' 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
  1.0::factA.
  0.02::factB.
  1.0::factC.
  %hop1
  0.2::factX:-and(factC,factA).
  0.6::factY:-or(factA,factC).
  0.05::factZ:-or(factA,factB).

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

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