Chances are about even that Greg is a rhino. It is impossible that Julius is a swan. There is a better than even chance that Mary went to the bedroom. It is impossible that if either 'Greg is a rhino' or 'Julius is a swan' but not both then Sandra left the milk. Chances are slight that if 'Julius is a swan' or 'Mary went to the bedroom' or both then John got the apple. There is a very good chance that if 'Julius is a swan and Greg is a rhino' then Lily is yellow.
Chances are about even that 'Lily is yellow' or 'Julius is a swan' or both.
It is impossible that 'Lily is yellow' or 'Julius is a swan' or both.
Chances are about even that 'Lily is yellow' or 'Julius is a swan' 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
  0.5::factA.
  0.0::factB.
  0.6::factC.
  %hop1
  0.0::factX:-xor(factA,factB).
  0.1::factY:-or(factB,factC).
  0.8::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Lily is yellow' or 'Julius is a swan' or both.