context: Chances are about even that Bernhard is gray. We believe that Lily is a swan. We doubt that Sandra took the apple.
hypothesis: It is probable that 'Lily is a swan and Sandra took the apple'.
valid_hypothesis: There is little chance that 'Lily is a swan and Sandra took the apple'.
invalid_hypothesis: It is probable that 'Lily is a swan and Sandra took the apple'.
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
    0.5::factA.
    0.75::factB.
    0.2::factC.
    
  
    %hop2
    conclusion:-and(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Lily is a swan and Sandra took the apple'.