There is a very good chance that Sandra got the football. There is a better than even chance that Brian is a frog. It is highly unlikely that Greg is white. Chances are about even that if 'Sandra got the football' or 'Greg is white' or both then John took the apple. It is unlikely that if either 'Sandra got the football' or 'Brian is a frog' but not both then Bernhard is white. We believe that if either 'Sandra got the football' or 'Greg is white' but not both then Julius is a lion.
It is impossible that either 'Julius is a lion' or 'Greg is white' but not both.
There is a better than even chance that either 'Julius is a lion' or 'Greg is white' but not both.
It is impossible that either 'Julius is a lion' or 'Greg is white' but not 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.
  0.6::factB.
  0.05::factC.
  %hop1
  0.5::factX:-or(factA,factC).
  0.2::factY:-xor(factA,factB).
  0.75::factZ:-xor(factA,factC).

  %hop2
  conclusion:-xor(factZ,factC).

  query(conclusion).
  
Either 'Julius is a lion' or 'Greg is white' but not both.