context: It is improbable that Bernhard is a swan. It is impossible that Brian is green. It is improbable that John left the apple.
hypothesis: It is certain that 'Brian is green' or 'John left the apple' or both.
valid_hypothesis: It is improbable that 'Brian is green' or 'John left the apple' or both.
invalid_hypothesis: It is certain that 'Brian is green' or 'John left 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
    0.1::factA.
    0.0::factB.
    0.1::factC.
    
  
    %hop2
    conclusion:-or(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is green' or 'John left the apple' or both.