context: It is probable that Sandra put down the milk. We doubt that Greg is a rhino. It is likely that Julius is gray.
hypothesis: Chances are about even that 'Julius is gray and Sandra put down the milk'.
valid_hypothesis: Chances are about even that 'Julius is gray and Sandra put down the milk'.
invalid_hypothesis: There is almost no chance that 'Julius is gray and Sandra put down the milk'.
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.
    0.2::factB.
    0.7::factC.
    
  
    %hop2
    conclusion:-and(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is gray and Sandra put down the milk'.