context: There is a better than even chance that Lily is a frog. Chances are about even that Greg is a swan. Chances are slight that Mary went to the bedroom.
hypothesis: We doubt that 'Greg is a swan' or 'Lily is a frog' or both.
valid_hypothesis: There is a very good chance that 'Greg is a swan' or 'Lily is a frog' or both.
invalid_hypothesis: We doubt that 'Greg is a swan' or 'Lily is a frog' 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
    0.6::factA.
    0.5::factB.
    0.1::factC.
    
  
    %hop2
    conclusion:-or(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a swan' or 'Lily is a frog' or both.