We doubt that Lily is a lion. There is a better than even chance that Julius is gray. It is probably the case that Greg is yellow. Chances are about even that if either 'Lily is a lion' or 'Julius is gray' but not both then Mary went to the kitchen. It is certain that if 'Julius is gray and Lily is a lion' then Sandra left the milk. It is unlikely that if 'Lily is a lion' or 'Julius is gray' or both then John got the apple.
It is certain that either 'Sandra left the milk' or 'Lily is a lion' but not both.
There is little chance that either 'Sandra left the milk' or 'Lily is a lion' but not both.
It is certain that either 'Sandra left the milk' or 'Lily is a lion' 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
  0.2::factA.
  0.6::factB.
  0.7::factC.
  %hop1
  0.5::factX:-xor(factA,factB).
  1.0::factY:-and(factB,factA).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
Either 'Sandra left the milk' or 'Lily is a lion' but not both.