Chances are slight that Greg is a swan. It is probably not the case that Jessica is a cat. It is unlikely that John put down the apple. It is certain that if 'Jessica is a cat and John put down the apple' then Gertrude is a sheep. It is improbable that if 'John put down the apple' or 'Jessica is a cat' or both then Bernhard is a swan. There is a better than even chance that if 'John put down the apple' or 'Jessica is a cat' or both then Julius is a rhino.
It is unlikely that either 'Jessica is a cat' or 'Julius is a rhino' but not both.
It is unlikely that either 'Jessica is a cat' or 'Julius is a rhino' but not both.
It is almost certain that either 'Jessica is a cat' or 'Julius 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
  0.1::factA.
  0.25::factB.
  0.2::factC.
  %hop1
  1.0::factX:-and(factB,factC).
  0.1::factY:-or(factC,factB).
  0.6::factZ:-or(factC,factB).

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

  query(conclusion).
  
Either 'Jessica is a cat' or 'Julius is a rhino' but not both.