context: It is likely that Lily is green. It is almost certain that Julius is a swan. It is unlikely that Mary discarded the milk. It is almost certain that if 'Julius is a swan' or 'Mary discarded the milk' or both then Antoine is thirsty. Chances are slight that if either 'Mary discarded the milk' or 'Julius is a swan' but not both then Bernhard is a frog. There is a better than even chance that if 'Mary discarded the milk and Julius is a swan' then John went to the garden.
hypothesis: It is improbable that either 'Lily is green' or 'Mary discarded the milk' but not both.
valid_hypothesis: There is a better than even chance that either 'Lily is green' or 'Mary discarded the milk' but not both.
invalid_hypothesis: It is improbable that either 'Lily is green' or 'Mary discarded the milk' 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
    0.7::factA.
    0.95::factB.
    0.2::factC.
    %hop1
    0.95::factX:-or(factB,factC).
    0.1::factY:-xor(factC,factB).
    0.6::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-xor(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is green' or 'Mary discarded the milk' but not both.