Chances are about even that Greg is white. It is certain that Bernhard is a rhino. There is a very good chance that Mary left the apple. There is a better than even chance that if either 'Mary left the apple' or 'Greg is white' but not both then John moved to the garden. There is a better than even chance that if 'Mary left the apple and Bernhard is a rhino' then Lily is a swan. It is highly unlikely that if 'Mary left the apple and Bernhard is a rhino' then Julius is gray.
Chances are about even that either 'Greg is white' or 'Mary left the apple' but not both.
Chances are about even that either 'Greg is white' or 'Mary left the apple' but not both.
It is highly unlikely that either 'Greg is white' or 'Mary left 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
  0.5::factA.
  1.0::factB.
  0.8::factC.
  %hop1
  0.6::factX:-xor(factC,factA).
  0.6::factY:-and(factC,factB).
  0.05::factZ:-and(factC,factB).

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

  query(conclusion).
  
Either 'Greg is white' or 'Mary left the apple' but not both.