context: It is probably not the case that Brian is yellow. It is almost certain that Lily is a rhino. It is impossible that Winona is a wolf. There is almost no chance that if 'Brian is yellow' or 'Lily is a rhino' or both then Greg is gray. It is probable that if 'Brian is yellow and Lily is a rhino' then Julius is white. We doubt that if 'Winona is a wolf and Brian is yellow' then Mary left the football.
hypothesis: There is a very good chance that either 'Brian is yellow' or 'Mary left the football' but not both.
valid_hypothesis: It is probably not the case that either 'Brian is yellow' or 'Mary left the football' but not both.
invalid_hypothesis: There is a very good chance that either 'Brian is yellow' or 'Mary left the football' 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.
    0.95::factB.
    0.0::factC.
    %hop1
    0.02::factX:-or(factA,factB).
    0.7::factY:-and(factA,factB).
    0.2::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-xor(factA,factZ).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Brian is yellow' or 'Mary left the football' but not both.