There is a very good chance that Jessica is a sheep. It is probable that Julius is a rhino. It is improbable that Brian is green. It is certain that if either 'Jessica is a sheep' or 'Brian is green' but not both then Jason is bored. It is highly likely that if 'Brian is green and Jessica is a sheep' then Mary left the apple. There is little chance that if either 'Julius is a rhino' or 'Brian is green' but not both then Lily is a swan.
It is probable that either 'Brian is green' or 'Lily is a swan' but not both.
We doubt that either 'Brian is green' or 'Lily is a swan' but not both.
It is probable that either 'Brian is green' or 'Lily is a swan' 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
  0.8::factA.
  0.7::factB.
  0.1::factC.
  %hop1
  1.0::factX:-xor(factA,factC).
  0.9::factY:-and(factC,factA).
  0.1::factZ:-xor(factB,factC).

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

  query(conclusion).
  
Either 'Brian is green' or 'Lily is a swan' but not both.