context: It is probably the case that Julius is a frog. Chances are slight that Greg is green. We doubt that Mary left the football.
hypothesis: There is almost no chance that 'Mary left the football and Greg is green'.
valid_hypothesis: There is almost no chance that 'Mary left the football and Greg is green'.
invalid_hypothesis: There is a very good chance that 'Mary left the football and Greg is green'.
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.
    0.1::factB.
    0.2::factC.
    
  
    %hop2
    conclusion:-and(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Mary left the football and Greg is green'.