It is impossible that Lily is green. Chances are slight that Sandra left the football. Chances are slight that Julius is white. It is certain that if either 'Julius is white' or 'Sandra left the football' but not both then Greg is a frog. It is probably not the case that if either 'Lily is green' or 'Sandra left the football' but not both then Mary went to the bedroom. It is unlikely that if 'Sandra left the football' or 'Julius is white' or both then Bernhard is white.
It is highly likely that either 'Bernhard is white' or 'Julius is white' but not both.
There is little chance that either 'Bernhard is white' or 'Julius is white' but not both.
It is highly likely that either 'Bernhard is white' or 'Julius 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
  0.0::factA.
  0.1::factB.
  0.1::factC.
  %hop1
  1.0::factX:-xor(factC,factB).
  0.25::factY:-xor(factA,factB).
  0.2::factZ:-or(factB,factC).

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

  query(conclusion).
  
Either 'Bernhard is white' or 'Julius is white' but not both.