We doubt that Mary went to the hallway. It is probably not the case that Sandra got the milk. It is impossible that Bernhard is a swan. It is likely that if 'Mary went to the hallway' or 'Bernhard is a swan' or both then Jessica is a sheep. It is certain that if either 'Bernhard is a swan' or 'Mary went to the hallway' but not both then Lily is a frog. We believe that if 'Bernhard is a swan and Mary went to the hallway' then Brian is a lion.
It is highly likely that either 'Bernhard is a swan' or 'Lily is a frog' but not both.
We doubt that either 'Bernhard is a swan' or 'Lily is a frog' but not both.
It is highly likely that either 'Bernhard is a swan' or 'Lily is a frog' 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.
  0.25::factB.
  0.0::factC.
  %hop1
  0.7::factX:-or(factA,factC).
  1.0::factY:-xor(factC,factA).
  0.75::factZ:-and(factC,factA).

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

  query(conclusion).
  
Either 'Bernhard is a swan' or 'Lily is a frog' but not both.