It is certain that Daniel put down the milk. There is a very good chance that Julius is a frog. It is improbable that Emily is a sheep. Chances are slight that if either 'Daniel put down the milk' or 'Emily is a sheep' but not both then Bernhard is green. We doubt that if either 'Emily is a sheep' or 'Julius is a frog' but not both then Brian is a rhino. It is probable that if 'Julius is a frog and Emily is a sheep' then Jason is tired.
It is certain that either 'Brian is a rhino' or 'Bernhard is green' but not both.
We doubt that either 'Brian is a rhino' or 'Bernhard is green' but not both.
It is certain that either 'Brian is a rhino' or 'Bernhard 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
  1.0::factA.
  0.8::factB.
  0.1::factC.
  %hop1
  0.1::factX:-xor(factA,factC).
  0.2::factY:-xor(factC,factB).
  0.7::factZ:-and(factB,factC).

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

  query(conclusion).
  
Either 'Brian is a rhino' or 'Bernhard is green' but not both.