context: It is probably the case that Greg is white. Chances are about even that John discarded the apple. It is certain that Bernhard is a swan.
hypothesis: It is probably not the case that 'Greg is white and John discarded the apple'.
valid_hypothesis: It is probably not the case that 'Greg is white and John discarded the apple'.
invalid_hypothesis: It is almost certain that 'Greg is white 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
    0.7::factA.
    0.5::factB.
    1.0::factC.
    
  
    %hop2
    conclusion:-and(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is white and John discarded the apple'.