context: There is a better than even chance that Greg is white. There is little chance that Mary got the football. There is almost no chance that Lily is a lion. There is little chance that if 'Mary got the football and Lily is a lion' then Bernhard is a swan. It is improbable that if 'Greg is white and Mary got the football' then Julius is gray. There is a better than even chance that if either 'Lily is a lion' or 'Mary got the football' but not both then John went to the garden.
hypothesis: It is certain that either 'Lily is a lion' or 'Julius is gray' but not both.
valid_hypothesis: There is almost no chance that either 'Lily is a lion' or 'Julius is gray' but not both.
invalid_hypothesis: It is certain that either 'Lily is a lion' or 'Julius is gray' 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
    0.6::factA.
    0.1::factB.
    0.02::factC.
    %hop1
    0.1::factX:-and(factB,factC).
    0.1::factY:-and(factA,factB).
    0.6::factZ:-xor(factC,factB).
  
    %hop2
    conclusion:-xor(factC,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is a lion' or 'Julius is gray' but not both.