context: It is improbable that Greg is yellow. It is almost certain that Winona is a sheep. We doubt that Fred is in the school.
hypothesis: There is almost no chance that 'Greg is yellow and Fred is in the school'.
valid_hypothesis: There is almost no chance that 'Greg is yellow and Fred is in the school'.
invalid_hypothesis: It is probably the case that 'Greg is yellow and Fred is in the school'.
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.
    0.95::factB.
    0.2::factC.
    
  
    %hop2
    conclusion:-and(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is yellow and Fred is in the school'.