context: Chances are slight that Greg is white. It is unlikely that John dropped the apple. It is impossible that Mary took the football.
hypothesis: There is almost no chance that 'John dropped the apple and Greg is white'.
valid_hypothesis: There is almost no chance that 'John dropped the apple and Greg is white'.
invalid_hypothesis: It is probable that 'John dropped the apple and Greg 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
    0.1::factA.
    0.2::factB.
    0.0::factC.
    
  
    %hop2
    conclusion:-and(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'John dropped the apple and Greg is white'.