context: It is certain that Mary got the milk. There is a very good chance that Greg is a rhino. We doubt that Lily is white.
hypothesis: It is probable that 'Lily is white and Greg is a rhino'.
valid_hypothesis: We doubt that 'Lily is white and Greg is a rhino'.
invalid_hypothesis: It is probable that 'Lily is white and Greg is a rhino'.
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.
    0.8::factB.
    0.2::factC.
    
  
    %hop2
    conclusion:-and(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Lily is white and Greg is a rhino'.