context: It is likely that Mary went to the hallway. It is almost certain that Lily is gray. We believe that Greg is a swan. It is unlikely that if 'Greg is a swan and Lily is gray' then Julius is a frog. It is highly likely that if 'Lily is gray and Greg is a swan' then Daniel grabbed the milk. It is likely that if 'Lily is gray' or 'Mary went to the hallway' or both then John moved to the garden.
hypothesis: Chances are about even that either 'John moved to the garden' or 'Daniel grabbed the milk' but not both.
valid_hypothesis: Chances are about even that either 'John moved to the garden' or 'Daniel grabbed the milk' but not both.
invalid_hypothesis: It is almost certain that either 'John moved to the garden' 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
    0.7::factA.
    0.95::factB.
    0.75::factC.
    %hop1
    0.2::factX:-and(factC,factB).
    0.9::factY:-and(factB,factC).
    0.7::factZ:-or(factB,factA).
  
    %hop2
    conclusion:-xor(factZ,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'John moved to the garden' or 'Daniel grabbed the milk' but not both.