It is probable that Brian is a frog. There is a better than even chance that Lily is white. It is highly likely that Julius is a swan. There is a better than even chance that if 'Brian is a frog' or 'Julius is a swan' or both then Jeff moved to the garden. We doubt that if 'Julius is a swan and Lily is white' then Gertrude is a sheep. There is a better than even chance that if 'Julius is a swan and Lily is white' then Winona is a wolf.
Chances are about even that either 'Winona is a wolf' or 'Jeff moved to the garden' but not both.
Chances are about even that either 'Winona is a wolf' or 'Jeff moved to the garden' but not both.
It is impossible that either 'Winona is a wolf' or 'Jeff moved to the garden' 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
  0.7::factA.
  0.6::factB.
  0.9::factC.
  %hop1
  0.6::factX:-or(factA,factC).
  0.2::factY:-and(factC,factB).
  0.6::factZ:-and(factC,factB).

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

  query(conclusion).
  
Either 'Winona is a wolf' or 'Jeff moved to the garden' but not both.