There is a better than even chance that Fred went to the garden. There is a very good chance that Bernhard is yellow. It is improbable that Julius is a swan. It is unlikely that if 'Julius is a swan and Bernhard is yellow' then Emily is a wolf. It is probably not the case that if 'Bernhard is yellow and Julius is a swan' then Daniel got the apple. It is certain that if either 'Julius is a swan' or 'Bernhard is yellow' but not both then Brian is a frog.
There is a very good chance that either 'Brian is a frog' or 'Julius is a swan' but not both.
There is a very good chance that either 'Brian is a frog' or 'Julius is a swan' but not both.
There is little chance that either 'Brian is a frog' or 'Julius 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
  0.6::factA.
  0.8::factB.
  0.1::factC.
  %hop1
  0.2::factX:-and(factC,factB).
  0.25::factY:-and(factB,factC).
  1.0::factZ:-xor(factC,factB).

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

  query(conclusion).
  
Either 'Brian is a frog' or 'Julius is a swan' but not both.