There is a better than even chance that Julius is yellow. We believe that Sandra left the milk. It is certain that Greg is green. It is impossible that if 'Greg is green' or 'Sandra left the milk' or both then Brian is white. There is a very good chance that if 'Greg is green' or 'Sandra left the milk' or both then Jason is tired. We believe that if 'Julius is yellow' or 'Sandra left the milk' or both then Jeff moved to the garden.
Chances are slight that either 'Brian is white' or 'Julius is yellow' but not both.
There is a better than even chance that either 'Brian is white' or 'Julius is yellow' but not both.
Chances are slight that either 'Brian is white' or 'Julius is yellow' 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.
  0.75::factB.
  1.0::factC.
  %hop1
  0.0::factX:-or(factC,factB).
  0.8::factY:-or(factC,factB).
  0.75::factZ:-or(factA,factB).

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

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