context: We believe that Brian is white. There is a very good chance that John got the apple. Chances are about even that Julius is a swan.
hypothesis: There is a very good chance that 'Julius is a swan and Brian is white'.
valid_hypothesis: It is probably not the case that 'Julius is a swan and Brian is white'.
invalid_hypothesis: There is a very good chance that 'Julius is a swan and Brian is white'.
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
    0.75::factA.
    0.8::factB.
    0.5::factC.
    
  
    %hop2
    conclusion:-and(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is a swan and Brian is white'.