It is highly unlikely that John left the apple. There is a very good chance that Greg is a frog. There is a better than even chance that Mary moved to the garden. It is probably not the case that if 'John left the apple and Greg is a frog' then Sumit is thirsty. Chances are slight that if 'Greg is a frog' or 'Mary moved to the garden' or both then Bernhard is yellow. Chances are slight that if 'Greg is a frog' or 'John left the apple' or both then Daniel got the apple.
Chances are slight that either 'Sumit is thirsty' or 'Mary moved to the garden' but not both.
There is a better than even chance that either 'Sumit is thirsty' or 'Mary moved to the garden' but not both.
Chances are slight that either 'Sumit is thirsty' or 'Mary moved to the garden' 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
  0.05::factA.
  0.8::factB.
  0.6::factC.
  %hop1
  0.25::factX:-and(factA,factB).
  0.1::factY:-or(factB,factC).
  0.1::factZ:-or(factB,factA).

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

  query(conclusion).
  
Either 'Sumit is thirsty' or 'Mary moved to the garden' but not both.