context: There is almost no chance that Brian is a lion. It is improbable that Lily is a frog. It is almost certain that Greg is gray. It is impossible that if either 'Lily is a frog' or 'Brian is a lion' but not both then Bill went to the kitchen. There is a very good chance that if 'Lily is a frog and Brian is a lion' then John moved to the garden. It is probably not the case that if 'Brian is a lion and Greg is gray' then Sandra got the football.
hypothesis: It is highly likely that either 'Greg is gray' or 'Lily is a frog' but not both.
valid_hypothesis: It is highly likely that either 'Greg is gray' or 'Lily is a frog' but not both.
invalid_hypothesis: It is unlikely that either 'Greg is gray' or 'Lily is a frog' 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
    0.02::factA.
    0.1::factB.
    0.95::factC.
    %hop1
    0.0::factX:-xor(factB,factA).
    0.8::factY:-and(factB,factA).
    0.25::factZ:-and(factA,factC).
  
    %hop2
    conclusion:-xor(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Greg is gray' or 'Lily is a frog' but not both.