It is highly likely that Bernhard is a frog. It is highly likely that Brian is yellow. It is almost certain that John dropped the milk. We believe that if either 'Bernhard is a frog' or 'Brian is yellow' but not both then Mary went to the garden. It is almost certain that if 'Brian is yellow and Bernhard is a frog' then Julius is a lion. It is improbable that if either 'Brian is yellow' or 'Bernhard is a frog' but not both then Greg is gray.
We believe that 'Julius is a lion and Brian is yellow'.
We believe that 'Julius is a lion and Brian is yellow'.
It is impossible that 'Julius is a lion and Brian is yellow'.

  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
  0.9::factA.
  0.9::factB.
  0.95::factC.
  %hop1
  0.75::factX:-xor(factA,factB).
  0.95::factY:-and(factB,factA).
  0.1::factZ:-xor(factB,factA).

  %hop2
  conclusion:-and(factY,factB).

  query(conclusion).
  
'Julius is a lion and Brian is yellow'.