context: It is certain that Bill went to the kitchen. It is unlikely that John discarded the apple. There is a very good chance that Bernhard is gray.
hypothesis: We doubt that 'Bernhard is gray and John discarded the apple'.
valid_hypothesis: We doubt that 'Bernhard is gray and John discarded the apple'.
invalid_hypothesis: There is a very good chance that 'Bernhard is gray and John discarded the apple'.
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
    1.0::factA.
    0.2::factB.
    0.8::factC.
    
  
    %hop2
    conclusion:-and(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is gray and John discarded the apple'.