context: We doubt that Julius is a frog. It is probably the case that Sandra left the milk. We believe that Bernhard is yellow.
hypothesis: It is probable that 'Bernhard is yellow and Julius is a frog'.
valid_hypothesis: Chances are slight that 'Bernhard is yellow and Julius is a frog'.
invalid_hypothesis: It is probable that 'Bernhard is yellow and Julius 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
    0.2::factA.
    0.7::factB.
    0.75::factC.
    
  
    %hop2
    conclusion:-and(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is yellow and Julius is a frog'.