context: There is almost no chance that Julius is a rhino. There is a very good chance that Lily is a swan. It is probably the case that Greg is a frog. We believe that if 'Julius is a rhino and Lily is a swan' then Sandra grabbed the apple. It is probably not the case that if either 'Julius is a rhino' or 'Greg is a frog' but not both then John moved to the office. It is almost certain that if 'Lily is a swan and Julius is a rhino' then Bernhard is green.
hypothesis: We doubt that either 'Lily is a swan' or 'John moved to the office' but not both.
valid_hypothesis: It is probable that either 'Lily is a swan' or 'John moved to the office' but not both.
invalid_hypothesis: We doubt that either 'Lily is a swan' or 'John moved to the office' 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
    0.02::factA.
    0.8::factB.
    0.7::factC.
    %hop1
    0.75::factX:-and(factA,factB).
    0.25::factY:-xor(factA,factC).
    0.95::factZ:-and(factB,factA).
  
    %hop2
    conclusion:-xor(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is a swan' or 'John moved to the office' but not both.