It is probably the case that Brian is a swan. It is certain that Bernhard is green. There is a better than even chance that Bill left the milk. It is certain that if either 'Brian is a swan' or 'Bill left the milk' but not both then Lily is a lion. There is a very good chance that if 'Brian is a swan and Bill left the milk' then Mary took the football. We believe that if 'Bill left the milk' or 'Brian is a swan' or both then John went to the bedroom.
It is probably not the case that 'Lily is a lion and Brian is a swan'.
It is probably not the case that 'Lily is a lion and Brian is a swan'.
We believe that 'Lily is a lion and Brian is a swan'.

  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
  0.7::factA.
  1.0::factB.
  0.6::factC.
  %hop1
  1.0::factX:-xor(factA,factC).
  0.8::factY:-and(factA,factC).
  0.75::factZ:-or(factC,factA).

  %hop2
  conclusion:-and(factX,factA).

  query(conclusion).
  
'Lily is a lion and Brian is a swan'.