context: It is probably not the case that Greg is a rhino. There is a very good chance that Brian is a swan. It is impossible that Julius is green. It is impossible that if 'Julius is green and Brian is a swan' then Bernhard is a frog. There is a very good chance that if either 'Julius is green' or 'Brian is a swan' but not both then Winona is a mouse. It is highly unlikely that if either 'Julius is green' or 'Greg is a rhino' but not both then John left the milk.
hypothesis: It is highly likely that either 'John left the milk' or 'Julius is green' but not both.
valid_hypothesis: There is almost no chance that either 'John left the milk' or 'Julius is green' but not both.
invalid_hypothesis: It is highly likely that either 'John left the milk' or 'Julius 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
    0.25::factA.
    0.8::factB.
    0.0::factC.
    %hop1
    0.0::factX:-and(factC,factB).
    0.8::factY:-xor(factC,factB).
    0.05::factZ:-xor(factC,factA).
  
    %hop2
    conclusion:-xor(factZ,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'John left the milk' or 'Julius is green' but not both.