There is almost no chance that Brian is green. There is a better than even chance that Daniel took the milk. Chances are slight that Mary left the football. We believe that if either 'Daniel took the milk' or 'Mary left the football' but not both then Bernhard is yellow. It is probably the case that if 'Mary left the football and Brian is green' then Fred went to the garden. It is highly unlikely that if 'Brian is green and Mary left the football' then Sumit is thirsty.
There is a better than even chance that either 'Brian is green' or 'Daniel took the milk' but not both.
There is a better than even chance that either 'Brian is green' or 'Daniel took the milk' but not both.
There is little chance that either 'Brian is green' or 'Daniel took 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
  0.02::factA.
  0.6::factB.
  0.1::factC.
  %hop1
  0.75::factX:-xor(factB,factC).
  0.7::factY:-and(factC,factA).
  0.05::factZ:-and(factA,factC).

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

  query(conclusion).
  
Either 'Brian is green' or 'Daniel took the milk' but not both.