context: It is certain that Mary took the football. There is little chance that John grabbed the milk. There is a better than even chance that Brian is a swan.
hypothesis: It is probably not the case that either 'Mary took the football' or 'John grabbed the milk' but not both.
valid_hypothesis: It is highly likely that either 'Mary took the football' or 'John grabbed the milk' but not both.
invalid_hypothesis: It is probably not the case that either 'Mary took the football' or 'John grabbed the milk' 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
    1.0::factA.
    0.1::factB.
    0.6::factC.
    
  
    %hop2
    conclusion:-xor(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Mary took the football' or 'John grabbed the milk' but not both.