context: We doubt that Daniel put down the milk. It is impossible that Bernhard is a swan. It is improbable that Greg is white. It is highly unlikely that if either 'Daniel put down the milk' or 'Greg is white' but not both then Gertrude is a mouse. Chances are about even that if 'Greg is white and Bernhard is a swan' then Julius is a lion. Chances are about even that if either 'Greg is white' or 'Daniel put down the milk' but not both then Mary went to the office.
hypothesis: It is impossible that 'Bernhard is a swan and Daniel put down the milk'.
valid_hypothesis: It is impossible that 'Bernhard is a swan and Daniel put down the milk'.
invalid_hypothesis: It is highly likely that 'Bernhard is a swan and Daniel put down the milk'.
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
    0.2::factA.
    0.0::factB.
    0.1::factC.
    %hop1
    0.05::factX:-xor(factA,factC).
    0.5::factY:-and(factC,factB).
    0.5::factZ:-xor(factC,factA).
  
    %hop2
    conclusion:-and(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is a swan and Daniel put down the milk'.