It is certain that Julius is white. It is probably not the case that Lily is yellow. There is a very good chance that John went to the bedroom. It is improbable that if 'Julius is white' or 'Lily is yellow' or both then Fred is in the cinema. It is certain that if 'Julius is white' or 'Lily is yellow' or both then Mary left the football. It is unlikely that if 'Julius is white' or 'Lily is yellow' or both then Bernhard is gray.
It is likely that either 'Mary left the football' or 'John went to the bedroom' but not both.
We doubt that either 'Mary left the football' or 'John went to the bedroom' but not both.
It is likely that either 'Mary left the football' or 'John went to the bedroom' 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
  1.0::factA.
  0.25::factB.
  0.8::factC.
  %hop1
  0.1::factX:-or(factA,factB).
  1.0::factY:-or(factA,factB).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
Either 'Mary left the football' or 'John went to the bedroom' but not both.