There is a very good chance that Greg is green. It is almost certain that Brian is a frog. It is probable that Mary took the milk. Chances are slight that if either 'Mary took the milk' or 'Brian is a frog' but not both then Julius is gray. It is almost certain that if 'Greg is green' or 'Brian is a frog' or both then Bernhard is gray. It is probable that if 'Greg is green' or 'Mary took the milk' or both then Lily is a swan.
It is highly likely that 'Lily is a swan' or 'Greg is green' or both.
It is highly likely that 'Lily is a swan' or 'Greg is green' or both.
Chances are slight that 'Lily is a swan' or 'Greg 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
  0.8::factA.
  0.95::factB.
  0.7::factC.
  %hop1
  0.1::factX:-xor(factC,factB).
  0.95::factY:-or(factA,factB).
  0.7::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Lily is a swan' or 'Greg is green' or both.