context: There is a very good chance that Bernhard is a swan. It is highly likely that Julius is white. It is likely that Yann is tired.
hypothesis: There is a better than even chance that 'Bernhard is a swan and Yann is tired'.
valid_hypothesis: There is a better than even chance that 'Bernhard is a swan and Yann is tired'.
invalid_hypothesis: Chances are slight that 'Bernhard is a swan and Yann is tired'.
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
    0.8::factA.
    0.9::factB.
    0.7::factC.
    
  
    %hop2
    conclusion:-and(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is a swan and Yann is tired'.