context: It is highly likely that Fred went to the garden. We believe that Jeff put down the milk. It is highly unlikely that Greg is green.
hypothesis: It is probably not the case that either 'Jeff put down the milk' or 'Fred went to the garden' but not both.
valid_hypothesis: It is probably not the case that either 'Jeff put down the milk' or 'Fred went to the garden' but not both.
invalid_hypothesis: It is almost certain that either 'Jeff put down the milk' or 'Fred went to the garden' 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
    0.9::factA.
    0.75::factB.
    0.05::factC.
    
  
    %hop2
    conclusion:-xor(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Jeff put down the milk' or 'Fred went to the garden' but not both.