context: There is almost no chance that Greg is white. It is improbable that Mary took the football. It is probable that Bernhard is a lion. It is probably the case that if either 'Bernhard is a lion' or 'Mary took the football' but not both then Julius is gray. It is impossible that if either 'Greg is white' or 'Bernhard is a lion' but not both then John discarded the apple. We doubt that if 'Bernhard is a lion and Greg is white' then Lily is a swan.
hypothesis: It is probably the case that either 'Greg is white' or 'Lily is a swan' but not both.
valid_hypothesis: There is almost no chance that either 'Greg is white' or 'Lily is a swan' but not both.
invalid_hypothesis: It is probably the case that either 'Greg is white' or 'Lily is a swan' 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.
    0.7::factC.
    %hop1
    0.7::factX:-xor(factC,factB).
    0.0::factY:-xor(factA,factC).
    0.2::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-xor(factA,factZ).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Greg is white' or 'Lily is a swan' but not both.