There is a better than even chance that Sandra left the milk. It is improbable that Lily is a rhino. There is little chance that Greg is green. We doubt that if either 'Greg is green' or 'Sandra left the milk' but not both then Julius is a swan. It is impossible that if 'Sandra left the milk' or 'Lily is a rhino' or both then Bernhard is white. We believe that if either 'Lily is a rhino' or 'Sandra left the milk' but not both then John discarded the apple.
Chances are about even that 'Lily is a rhino' or 'John discarded the apple' or both.
Chances are about even that 'Lily is a rhino' or 'John discarded the apple' or both.
It is certain that 'Lily is a rhino' or 'John discarded the apple' 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
  0.6::factA.
  0.1::factB.
  0.1::factC.
  %hop1
  0.2::factX:-xor(factC,factA).
  0.0::factY:-or(factA,factB).
  0.75::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Lily is a rhino' or 'John discarded the apple' or both.