context: There is almost no chance that Sandra left the milk. Chances are slight that John moved to the garden. It is highly unlikely that Greg is yellow.
hypothesis: It is impossible that 'Greg is yellow and Sandra left the milk'.
valid_hypothesis: It is impossible that 'Greg is yellow and Sandra left the milk'.
invalid_hypothesis: We believe that 'Greg is yellow and Sandra left 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
    0.02::factA.
    0.1::factB.
    0.05::factC.
    
  
    %hop2
    conclusion:-and(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is yellow and Sandra left the milk'.