There is a better than even chance that Greg is white. There is almost no chance that Bernhard is a frog. It is highly likely that Mary left the football. We doubt that if 'Bernhard is a frog and Mary left the football' then Julius is a swan. It is almost certain that if 'Greg is white' or 'Bernhard is a frog' or both then John took the apple. It is probably the case that if either 'Bernhard is a frog' or 'Greg is white' but not both then Winona is a wolf.
There is a better than even chance that 'Julius is a swan' or 'Greg is white' or both.
There is a better than even chance that 'Julius is a swan' or 'Greg is white' or both.
It is improbable that 'Julius is a swan' or 'Greg is white' 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.
  0.02::factB.
  0.9::factC.
  %hop1
  0.2::factX:-and(factB,factC).
  0.95::factY:-or(factA,factB).
  0.7::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Julius is a swan' or 'Greg is white' or both.