context: It is impossible that Mary went to the hallway. It is certain that Lily is white. There is little chance that Greg is a rhino.
hypothesis: Chances are slight that either 'Lily is white' or 'Greg is a rhino' but not both.
valid_hypothesis: It is highly likely that either 'Lily is white' or 'Greg is a rhino' but not both.
invalid_hypothesis: Chances are slight that either 'Lily is white' or 'Greg 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
    0.0::factA.
    1.0::factB.
    0.1::factC.
    
  
    %hop2
    conclusion:-xor(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is white' or 'Greg is a rhino' but not both.