context: It is improbable that Bernhard is a swan. It is highly likely that Mary dropped the milk. Chances are about even that Julius is gray.
hypothesis: There is almost no chance that 'Julius is gray and Mary dropped the milk'.
valid_hypothesis: Chances are about even that 'Julius is gray and Mary dropped the milk'.
invalid_hypothesis: There is almost no chance that 'Julius is gray and Mary dropped the milk'.
problog: 
    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.
    0.9::factB.
    0.5::factC.
    
  
    %hop2
    conclusion:-and(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is gray and Mary dropped the milk'.