There is a better than even chance that Jason is tired. There is little chance that Sandra left the milk. There is almost no chance that Julius is a swan. It is probable that if 'Sandra left the milk' or 'Julius is a swan' or both then John went to the garden. There is a better than even chance that if 'Julius is a swan' or 'Jason is tired' or both then Bernhard is yellow. It is almost certain that if 'Sandra left the milk and Julius is a swan' then Greg is white.
Chances are about even that either 'Bernhard is yellow' or 'Sandra left the milk' but not both.
Chances are about even that either 'Bernhard is yellow' or 'Sandra left the milk' but not both.
It is impossible that either 'Bernhard is yellow' or 'Sandra left the milk' 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
  0.6::factA.
  0.1::factB.
  0.02::factC.
  %hop1
  0.7::factX:-or(factB,factC).
  0.6::factY:-or(factC,factA).
  0.95::factZ:-and(factB,factC).

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

  query(conclusion).
  
Either 'Bernhard is yellow' or 'Sandra left the milk' but not both.