Chances are about even that Jeff moved to the office. It is certain that Brian is white. It is impossible that Julius is a lion. There is a very good chance that if 'Julius is a lion and Brian is white' then Lily is gray. It is probably not the case that if 'Jeff moved to the office and Julius is a lion' then John left the apple. It is impossible that if either 'Julius is a lion' or 'Jeff moved to the office' but not both then Mary went to the office.
Chances are about even that either 'John left the apple' or 'Jeff moved to the office' but not both.
Chances are about even that either 'John left the apple' or 'Jeff moved to the office' but not both.
It is almost certain that either 'John left the apple' or 'Jeff 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
  0.5::factA.
  1.0::factB.
  0.0::factC.
  %hop1
  0.8::factX:-and(factC,factB).
  0.25::factY:-and(factA,factC).
  0.0::factZ:-xor(factC,factA).

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

  query(conclusion).
  
Either 'John left the apple' or 'Jeff moved to the office' but not both.