context: It is highly likely that Bernhard is gray. We believe that Lily is a swan. There is little chance that Julius is green.
hypothesis: It is likely that 'Bernhard is gray and Lily is a swan'.
valid_hypothesis: It is likely that 'Bernhard is gray and Lily is a swan'.
invalid_hypothesis: It is unlikely that 'Bernhard is gray and Lily is a swan'.
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
    0.9::factA.
    0.75::factB.
    0.1::factC.
    
  
    %hop2
    conclusion:-and(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is gray and Lily is a swan'.