context: It is highly unlikely that Brian is green. It is probably not the case that John went to the garden. Chances are about even that Bernhard is a swan. There is almost no chance that if either 'Brian is green' or 'Bernhard is a swan' but not both then Gertrude is a cat. There is almost no chance that if 'Bernhard is a swan' or 'Brian is green' or both then Mary left the milk. There is almost no chance that if either 'John went to the garden' or 'Bernhard is a swan' but not both then Greg is a swan.
hypothesis: It is highly unlikely that 'Mary left the milk' or 'Brian is green' or both.
valid_hypothesis: It is highly unlikely that 'Mary left the milk' or 'Brian is green' or both.
invalid_hypothesis: It is highly likely that 'Mary left the milk' or 'Brian is green' or 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
    0.05::factA.
    0.25::factB.
    0.5::factC.
    %hop1
    0.02::factX:-xor(factA,factC).
    0.02::factY:-or(factC,factA).
    0.02::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-or(factY,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Mary left the milk' or 'Brian is green' or both.