context: It is probably the case that Bernhard is a frog. There is almost no chance that Jessica is a cat. It is probably not the case that Sandra took the football.
hypothesis: We believe that 'Bernhard is a frog' or 'Sandra took the football' or both.
valid_hypothesis: We believe that 'Bernhard is a frog' or 'Sandra took the football' or both.
invalid_hypothesis: Chances are slight that 'Bernhard is a frog' or 'Sandra took the football' 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
    0.7::factA.
    0.02::factB.
    0.25::factC.
    
  
    %hop2
    conclusion:-or(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is a frog' or 'Sandra took the football' or both.