context: There is almost no chance that John went to the kitchen. We believe that Fred discarded the apple. It is certain that Lily is white.
hypothesis: We believe that either 'John went to the kitchen' or 'Fred discarded the apple' but not both.
valid_hypothesis: We believe that either 'John went to the kitchen' or 'Fred discarded the apple' but not both.
invalid_hypothesis: There is almost no chance that either 'John went to the kitchen' or 'Fred discarded the apple' 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
    0.02::factA.
    0.75::factB.
    1.0::factC.
    
  
    %hop2
    conclusion:-xor(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'John went to the kitchen' or 'Fred discarded the apple' but not both.