Chances are slight that Brian is a lion. It is improbable that Greg is gray. There is a very good chance that Julius is a frog. It is likely that if 'Julius is a frog and Brian is a lion' then Daniel dropped the milk. There is a better than even chance that if either 'Greg is gray' or 'Julius is a frog' but not both then John moved to the office. It is unlikely that if 'Greg is gray and Brian is a lion' then Lily is a swan.
Chances are about even that either 'Julius is a frog' or 'John moved to the office' but not both.
Chances are about even that either 'Julius is a frog' or 'John moved to the office' but not both.
It is certain that either 'Julius is a frog' or 'John moved to 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
  0.1::factA.
  0.1::factB.
  0.8::factC.
  %hop1
  0.7::factX:-and(factC,factA).
  0.6::factY:-xor(factB,factC).
  0.2::factZ:-and(factB,factA).

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

  query(conclusion).
  
Either 'Julius is a frog' or 'John moved to the office' but not both.