context: It is improbable that Mary grabbed the milk. It is highly likely that Julius is a swan. There is a very good chance that John moved to the office. It is probably the case that if either 'Julius is a swan' or 'Mary grabbed the milk' but not both then Greg is a frog. It is impossible that if 'John moved to the office and Julius is a swan' then Winona is a wolf. It is probably not the case that if 'Mary grabbed the milk and Julius is a swan' then Bernhard is a frog.
hypothesis: It is improbable that either 'Bernhard is a frog' or 'Julius is a swan' but not both.
valid_hypothesis: It is highly likely that either 'Bernhard is a frog' or 'Julius is a swan' but not both.
invalid_hypothesis: It is improbable that either 'Bernhard is a frog' or 'Julius is a swan' 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
    0.1::factA.
    0.9::factB.
    0.8::factC.
    %hop1
    0.7::factX:-xor(factB,factA).
    0.0::factY:-and(factC,factB).
    0.25::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-xor(factZ,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Bernhard is a frog' or 'Julius is a swan' but not both.