There is a better than even chance that Greg is a rhino. It is unlikely that John dropped the milk. It is probably not the case that Daniel got the apple. There is a very good chance that if either 'John dropped the milk' or 'Greg is a rhino' but not both then Fred is in the office. There is a better than even chance that if 'John dropped the milk' or 'Daniel got the apple' or both then Lily is a lion. It is almost certain that if 'Daniel got the apple and Greg is a rhino' then Brian is white.
Chances are about even that either 'Brian is white' or 'Fred is in the office' but not both.
Chances are about even that either 'Brian is white' or 'Fred is in the office' but not both.
There is almost no chance that either 'Brian is white' or 'Fred is in the office' 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.
  0.2::factB.
  0.25::factC.
  %hop1
  0.8::factX:-xor(factB,factA).
  0.6::factY:-or(factB,factC).
  0.95::factZ:-and(factC,factA).

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

  query(conclusion).
  
Either 'Brian is white' or 'Fred is in the office' but not both.