context: It is unlikely that John left the apple. There is a better than even chance that Greg is yellow. It is probably not the case that Lily is white.
hypothesis: There is a very good chance that either 'John left the apple' or 'Lily is white' but not both.
valid_hypothesis: It is probably not the case that either 'John left the apple' or 'Lily is white' but not both.
invalid_hypothesis: There is a very good chance that either 'John left the apple' or 'Lily is white' 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
    0.2::factA.
    0.6::factB.
    0.25::factC.
    
  
    %hop2
    conclusion:-xor(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'John left the apple' or 'Lily is white' but not both.