There is a better than even chance that Lily is a swan. It is highly likely that Mary took the football. There is almost no chance that Brian is green. Chances are about even that if either 'Mary took the football' or 'Lily is a swan' but not both then Winona is a wolf. It is highly likely that if either 'Lily is a swan' or 'Mary took the football' but not both then Jessica is a cat. It is highly likely that if either 'Lily is a swan' or 'Mary took the football' but not both then Julius is a frog.
It is highly likely that 'Julius is a frog' or 'Lily is a swan' or both.
It is highly likely that 'Julius is a frog' or 'Lily is a swan' or both.
It is probably not the case that 'Julius is a frog' or 'Lily 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
  0.6::factA.
  0.9::factB.
  0.02::factC.
  %hop1
  0.5::factX:-xor(factB,factA).
  0.9::factY:-xor(factA,factB).
  0.9::factZ:-xor(factA,factB).

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

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