context: It is almost certain that John got the apple. There is almost no chance that Gertrude is a sheep. It is highly likely that Mary is in the school.
hypothesis: Chances are slight that either 'John got the apple' or 'Mary is in the school' but not both.
valid_hypothesis: Chances are slight that either 'John got the apple' or 'Mary is in the school' but not both.
invalid_hypothesis: It is likely that either 'John got the apple' or 'Mary is in the school' but not 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
    0.95::factA.
    0.02::factB.
    0.9::factC.
    
  
    %hop2
    conclusion:-xor(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'John got the apple' or 'Mary is in the school' but not both.