context: It is probably not the case that Greg is green. There is a better than even chance that Daniel grabbed the milk. It is probable that Gertrude is a sheep. It is highly likely that if 'Gertrude is a sheep and Daniel grabbed the milk' then Julius is yellow. There is a better than even chance that if either 'Daniel grabbed the milk' or 'Gertrude is a sheep' but not both then John moved to the office. It is almost certain that if 'Gertrude is a sheep' or 'Daniel grabbed the milk' or both then Brian is white.
hypothesis: We believe that either 'Brian is white' or 'Daniel grabbed the milk' but not both.
valid_hypothesis: It is probably not the case that either 'Brian is white' or 'Daniel grabbed the milk' but not both.
invalid_hypothesis: We believe that either 'Brian is white' or 'Daniel 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
    0.25::factA.
    0.6::factB.
    0.7::factC.
    %hop1
    0.9::factX:-and(factC,factB).
    0.6::factY:-xor(factB,factC).
    0.95::factZ:-or(factC,factB).
  
    %hop2
    conclusion:-xor(factZ,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Brian is white' or 'Daniel grabbed the milk' but not both.