There is little chance that Bernhard is a lion. It is probable that John went to the garden. We believe that Lily is a rhino. It is likely that if 'Lily is a rhino' or 'Bernhard is a lion' or both then Jeff discarded the milk. It is likely that if either 'John went to the garden' or 'Bernhard is a lion' but not both then Fred dropped the apple. It is highly unlikely that if either 'Bernhard is a lion' or 'John went to the garden' but not both then Julius is a frog.
It is almost certain that either 'Bernhard is a lion' or 'Julius is a frog' but not both.
Chances are slight that either 'Bernhard is a lion' or 'Julius is a frog' but not both.
It is almost certain that either 'Bernhard is a lion' or 'Julius 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
  0.1::factA.
  0.7::factB.
  0.75::factC.
  %hop1
  0.7::factX:-or(factC,factA).
  0.7::factY:-xor(factB,factA).
  0.05::factZ:-xor(factA,factB).

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

  query(conclusion).
  
Either 'Bernhard is a lion' or 'Julius is a frog' but not both.