context: It is impossible that Greg is white. It is probably not the case that Mary got the apple. We believe that John went to the garden.
hypothesis: There is a very good chance that 'John went to the garden' or 'Mary got the apple' or both.
valid_hypothesis: There is a very good chance that 'John went to the garden' or 'Mary got the apple' or both.
invalid_hypothesis: It is improbable that 'John went to the garden' or 'Mary got 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
    0.0::factA.
    0.25::factB.
    0.75::factC.
    
  
    %hop2
    conclusion:-or(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'John went to the garden' or 'Mary got the apple' or both.