It is unlikely that Julius is a rhino. It is improbable that Bernhard is a lion. There is a very good chance that Brian is green. It is likely that if 'Julius is a rhino' or 'Brian is green' or both then Mary got the football. Chances are slight that if either 'Bernhard is a lion' or 'Julius is a rhino' but not both then Daniel took the apple. There is a better than even chance that if 'Brian is green and Julius is a rhino' then Greg is a swan.
We believe that either 'Daniel took the apple' or 'Greg is a swan' but not both.
It is improbable that either 'Daniel took the apple' or 'Greg is a swan' but not both.
We believe that either 'Daniel took the apple' or 'Greg is a swan' 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
  0.2::factA.
  0.1::factB.
  0.8::factC.
  %hop1
  0.7::factX:-or(factA,factC).
  0.1::factY:-xor(factB,factA).
  0.6::factZ:-and(factC,factA).

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

  query(conclusion).
  
Either 'Daniel took the apple' or 'Greg is a swan' but not both.