context: It is improbable that Sandra left the milk. Chances are about even that Bernhard is a swan. It is highly likely that Lily is a swan. We doubt that if 'Bernhard is a swan and Sandra left the milk' then Julius is white. There is a better than even chance that if 'Lily is a swan and Sandra left the milk' then Brian is yellow. We believe that if either 'Lily is a swan' or 'Sandra left the milk' but not both then Mary moved to the garden.
hypothesis: There is a very good chance that 'Bernhard is a swan and Mary moved to the garden'.
valid_hypothesis: It is probably not the case that 'Bernhard is a swan and Mary moved to the garden'.
invalid_hypothesis: There is a very good chance that 'Bernhard is a swan and Mary moved to the garden'.
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
    0.1::factA.
    0.5::factB.
    0.9::factC.
    %hop1
    0.2::factX:-and(factB,factA).
    0.6::factY:-and(factC,factA).
    0.75::factZ:-xor(factC,factA).
  
    %hop2
    conclusion:-and(factB,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is a swan and Mary moved to the garden'.