It is likely that Jessica is a cat. It is certain that Brian is a rhino. There is little chance that Greg is a lion. Chances are slight that if 'Jessica is a cat' or 'Greg is a lion' or both then Gertrude is a sheep. We doubt that if either 'Jessica is a cat' or 'Brian is a rhino' but not both then Lily is green. Chances are about even that if either 'Brian is a rhino' or 'Greg is a lion' but not both then Daniel left the apple.
There is little chance that either 'Brian is a rhino' or 'Daniel left the apple' but not both.
There is a better than even chance that either 'Brian is a rhino' or 'Daniel left the apple' but not both.
There is little chance that either 'Brian is a rhino' or 'Daniel left the apple' 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.
  1.0::factB.
  0.1::factC.
  %hop1
  0.1::factX:-or(factA,factC).
  0.2::factY:-xor(factA,factB).
  0.5::factZ:-xor(factB,factC).

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

  query(conclusion).
  
Either 'Brian is a rhino' or 'Daniel left the apple' but not both.