context: There is almost no chance that Bernhard is yellow. We believe that Greg is a rhino. It is probable that Gertrude is a wolf.
hypothesis: We doubt that either 'Gertrude is a wolf' or 'Bernhard is yellow' but not both.
valid_hypothesis: It is likely that either 'Gertrude is a wolf' or 'Bernhard is yellow' but not both.
invalid_hypothesis: We doubt that either 'Gertrude is a wolf' or 'Bernhard is yellow' 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.
    0.7::factC.
    
  
    %hop2
    conclusion:-xor(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Gertrude is a wolf' or 'Bernhard is yellow' but not both.