It is improbable that Julius is a rhino. It is highly unlikely that Sandra grabbed the apple. It is probably the case that Greg is a lion. It is improbable that if 'Julius is a rhino' or 'Sandra grabbed the apple' or both then John got the milk. It is certain that if 'Greg is a lion and Julius is a rhino' then Lily is white. It is probable that if either 'Greg is a lion' or 'Julius is a rhino' but not both then Mary went to the garden.
There is almost no chance that either 'Greg is a lion' or 'Sandra grabbed the apple' but not both.
It is probable that either 'Greg is a lion' or 'Sandra grabbed the apple' but not both.
There is almost no chance that either 'Greg is a lion' or 'Sandra grabbed the apple' 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
  0.1::factA.
  0.05::factB.
  0.7::factC.
  %hop1
  0.1::factX:-or(factA,factB).
  1.0::factY:-and(factC,factA).
  0.7::factZ:-xor(factC,factA).

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

  query(conclusion).
  
Either 'Greg is a lion' or 'Sandra grabbed the apple' but not both.