context: It is certain that Gertrude is a mouse. It is probably the case that Lily is a rhino. Chances are about even that Brian is a frog.
hypothesis: It is probable that 'Lily is a rhino and Brian is a frog'.
valid_hypothesis: It is probably not the case that 'Lily is a rhino and Brian is a frog'.
invalid_hypothesis: It is probable that 'Lily is a rhino and Brian is a frog'.
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.
    0.7::factB.
    0.5::factC.
    
  
    %hop2
    conclusion:-and(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Lily is a rhino and Brian is a frog'.