context: It is unlikely that Brian is a rhino. It is probable that Daniel dropped the milk. It is impossible that John put down the apple.
hypothesis: It is improbable that either 'Daniel dropped the milk' or 'Brian is a rhino' but not both.
valid_hypothesis: There is a better than even chance that either 'Daniel dropped the milk' or 'Brian is a rhino' but not both.
invalid_hypothesis: It is improbable that either 'Daniel dropped the milk' or 'Brian is a rhino' 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.
    0.7::factB.
    0.0::factC.
    
  
    %hop2
    conclusion:-xor(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Daniel dropped the milk' or 'Brian is a rhino' but not both.