context: We doubt that Brian is a swan. It is probably not the case that Mary picked up the apple. It is impossible that Bernhard is gray.
hypothesis: Chances are about even that 'Brian is a swan' or 'Mary picked up the apple' or both.
valid_hypothesis: Chances are about even that 'Brian is a swan' or 'Mary picked up the apple' or both.
invalid_hypothesis: It is certain that 'Brian is a swan' or 'Mary picked up the apple' 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
    0.2::factA.
    0.25::factB.
    0.0::factC.
    
  
    %hop2
    conclusion:-or(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a swan' or 'Mary picked up the apple' or both.