There is a very good chance that Bernhard is a frog. It is improbable that Julius is a lion. It is probably the case that John went to the garden. It is certain that if either 'John went to the garden' or 'Julius is a lion' but not both then Greg is a frog. It is probable that if 'Bernhard is a frog and John went to the garden' then Daniel got the milk. There is a very good chance that if 'Bernhard is a frog' or 'John went to the garden' or both then Fred discarded the apple.
It is impossible that either 'John went to the garden' or 'Julius is a lion' but not both.
It is probably the case that either 'John went to the garden' or 'Julius is a lion' but not both.
It is impossible that either 'John went to the garden' or 'Julius is a lion' 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.
  0.1::factB.
  0.7::factC.
  %hop1
  1.0::factX:-xor(factC,factB).
  0.7::factY:-and(factA,factC).
  0.8::factZ:-or(factA,factC).

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

  query(conclusion).
  
Either 'John went to the garden' or 'Julius is a lion' but not both.