There is little chance that John got the apple. It is certain that Bernhard is gray. Chances are slight that Sandra took the football. It is highly unlikely that if either 'Sandra took the football' or 'Bernhard is gray' but not both then Julius is a swan. We believe that if 'Sandra took the football and Bernhard is gray' then Sumit is bored. Chances are slight that if either 'Sandra took the football' or 'John got the apple' but not both then Lily is green.
There is a better than even chance that either 'John got the apple' or 'Lily is green' but not both.
It is improbable that either 'John got the apple' or 'Lily is green' but not both.
There is a better than even chance that either 'John got the apple' or 'Lily is green' 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
  0.1::factA.
  1.0::factB.
  0.1::factC.
  %hop1
  0.05::factX:-xor(factC,factB).
  0.75::factY:-and(factC,factB).
  0.1::factZ:-xor(factC,factA).

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

  query(conclusion).
  
Either 'John got the apple' or 'Lily is green' but not both.