There is almost no chance that Lily is a swan. Chances are about even that Emily is a cat. Chances are slight that Mary dropped the apple. It is probably the case that if either 'Lily is a swan' or 'Emily is a cat' but not both then Gertrude is a wolf. There is a very good chance that if either 'Emily is a cat' or 'Mary dropped the apple' but not both then John went to the garden. Chances are slight that if 'Mary dropped the apple' or 'Lily is a swan' or both then Julius is yellow.
It is probably not the case that either 'Gertrude is a wolf' or 'Julius is yellow' but not both.
It is probably not the case that either 'Gertrude is a wolf' or 'Julius is yellow' but not both.
It is almost certain that either 'Gertrude is a wolf' or 'Julius is yellow' 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
  0.02::factA.
  0.5::factB.
  0.1::factC.
  %hop1
  0.7::factX:-xor(factA,factB).
  0.8::factY:-xor(factB,factC).
  0.1::factZ:-or(factC,factA).

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

  query(conclusion).
  
Either 'Gertrude is a wolf' or 'Julius is yellow' but not both.