Chances are about even that Emily is a wolf. It is impossible that Lily is a swan. There is almost no chance that Mary got the apple. It is almost certain that if 'Emily is a wolf' or 'Lily is a swan' or both then John dropped the milk. We doubt that if 'Mary got the apple' or 'Lily is a swan' or both then Jessica is a cat. It is unlikely that if 'Mary got the apple and Emily is a wolf' then Bernhard is green.
It is impossible that either 'Bernhard is green' or 'Emily is a wolf' but not both.
Chances are about even that either 'Bernhard is green' or 'Emily is a wolf' but not both.
It is impossible that either 'Bernhard is green' or 'Emily is a wolf' 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.
  0.0::factB.
  0.02::factC.
  %hop1
  0.95::factX:-or(factA,factB).
  0.2::factY:-or(factC,factB).
  0.2::factZ:-and(factC,factA).

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

  query(conclusion).
  
Either 'Bernhard is green' or 'Emily is a wolf' but not both.