context: There is almost no chance that Julius is a swan. We doubt that Emily is a mouse. It is impossible that Bernhard is green. It is probably the case that if 'Julius is a swan and Emily is a mouse' then Brian is a swan. We believe that if 'Emily is a mouse' or 'Julius is a swan' or both then Lily is a lion. It is unlikely that if 'Emily is a mouse' or 'Julius is a swan' or both then John moved to the garden.
hypothesis: Chances are about even that either 'Brian is a swan' or 'Bernhard is green' but not both.
valid_hypothesis: It is impossible that either 'Brian is a swan' or 'Bernhard is green' but not both.
invalid_hypothesis: Chances are about even that either 'Brian is a swan' or 'Bernhard is green' 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.
    0.2::factB.
    0.0::factC.
    %hop1
    0.7::factX:-and(factA,factB).
    0.75::factY:-or(factB,factA).
    0.2::factZ:-or(factB,factA).
  
    %hop2
    conclusion:-xor(factX,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Brian is a swan' or 'Bernhard is green' but not both.