We doubt that Jessica is a cat. It is improbable that Brian is green. Chances are about even that Julius is a rhino. Chances are slight that if 'Julius is a rhino' or 'Brian is green' or both then Mary got the football. It is highly unlikely that if either 'Brian is green' or 'Jessica is a cat' but not both then Bernhard is a lion. It is probably not the case that if 'Brian is green and Julius is a rhino' then Bill left the milk.
It is probably not the case that either 'Jessica is a cat' or 'Brian is green' but not both.
It is probably not the case that either 'Jessica is a cat' or 'Brian is green' but not both.
It is probable that either 'Jessica is a cat' or 'Brian is green' 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
  0.2::factA.
  0.1::factB.
  0.5::factC.
  %hop1
  0.1::factX:-or(factC,factB).
  0.05::factY:-xor(factB,factA).
  0.25::factZ:-and(factB,factC).

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

  query(conclusion).
  
Either 'Jessica is a cat' or 'Brian is green' but not both.