context: It is certain that Mary moved to the garden. It is improbable that John got the milk. Chances are slight that Brian is a frog.
hypothesis: It is likely that 'Brian is a frog' or 'John got the milk' or both.
valid_hypothesis: We doubt that 'Brian is a frog' or 'John got the milk' or both.
invalid_hypothesis: It is likely that 'Brian is a frog' or 'John got the milk' or both.
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.
    0.1::factB.
    0.1::factC.
    
  
    %hop2
    conclusion:-or(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a frog' or 'John got the milk' or both.