context: Chances are about even that Jeff moved to the garden. We believe that Mary got the football. It is certain that Lily is yellow. There is almost no chance that if 'Mary got the football and Jeff moved to the garden' then Winona is a mouse. It is certain that if 'Mary got the football' or 'Jeff moved to the garden' or both then Bill went to the kitchen. There is a better than even chance that if 'Lily is yellow' or 'Jeff moved to the garden' or both then Brian is white.
hypothesis: Chances are about even that either 'Mary got the football' or 'Jeff moved to the garden' but not both.
valid_hypothesis: Chances are about even that either 'Mary got the football' or 'Jeff moved to the garden' but not both.
invalid_hypothesis: It is highly unlikely that either 'Mary got the football' or 'Jeff moved to the garden' 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
    0.5::factA.
    0.75::factB.
    1.0::factC.
    %hop1
    0.02::factX:-and(factB,factA).
    1.0::factY:-or(factB,factA).
    0.6::factZ:-or(factC,factA).
  
    %hop2
    conclusion:-xor(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Mary got the football' or 'Jeff moved to the garden' but not both.