There is a better than even chance that John discarded the milk. It is certain that Julius is a frog. It is probable that Mary left the apple. It is probable that if 'John discarded the milk' or 'Mary left the apple' or both then Gertrude is a cat. It is impossible that if either 'Mary left the apple' or 'John discarded the milk' but not both then Jessica is a sheep. There is a better than even chance that if 'Julius is a frog and John discarded the milk' then Lily is a rhino.
Chances are about even that either 'Gertrude is a cat' or 'Lily is a rhino' but not both.
Chances are about even that either 'Gertrude is a cat' or 'Lily is a rhino' but not both.
There is almost no chance that either 'Gertrude is a cat' or 'Lily is a rhino' 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
  0.6::factA.
  1.0::factB.
  0.7::factC.
  %hop1
  0.7::factX:-or(factA,factC).
  0.0::factY:-xor(factC,factA).
  0.6::factZ:-and(factB,factA).

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

  query(conclusion).
  
Either 'Gertrude is a cat' or 'Lily is a rhino' but not both.