There is a very good chance that Julius is a swan. It is probable that John moved to the garden. It is unlikely that Emily is a sheep. It is impossible that if 'Emily is a sheep' or 'Julius is a swan' or both then Winona is a mouse. Chances are slight that if 'Emily is a sheep and Julius is a swan' then Bernhard is green. It is probable that if 'Emily is a sheep and Julius is a swan' then Brian is yellow.
Chances are about even that either 'John moved to the garden' or 'Julius is a swan' but not both.
Chances are about even that either 'John moved to the garden' or 'Julius is a swan' but not both.
It is impossible that either 'John moved to the garden' or 'Julius is a swan' 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
  0.8::factA.
  0.7::factB.
  0.2::factC.
  %hop1
  0.0::factX:-or(factC,factA).
  0.1::factY:-and(factC,factA).
  0.7::factZ:-and(factC,factA).

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

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