There is a better than even chance that Daniel left the apple. There is a very good chance that Sandra put down the milk. Chances are slight that Bernhard is a frog. There is a better than even chance that if 'Daniel left the apple' or 'Bernhard is a frog' or both then Greg is gray. We doubt that if 'Bernhard is a frog' or 'Daniel left the apple' or both then Lily is a lion. It is highly unlikely that if 'Bernhard is a frog and Daniel left the apple' then Winona is a sheep.
It is almost certain that either 'Daniel left the apple' or 'Lily is a lion' but not both.
Chances are about even that either 'Daniel left the apple' or 'Lily is a lion' but not both.
It is almost certain that either 'Daniel left the apple' 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
  0.6::factA.
  0.8::factB.
  0.1::factC.
  %hop1
  0.6::factX:-or(factA,factC).
  0.2::factY:-or(factC,factA).
  0.05::factZ:-and(factC,factA).

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

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