context: It is likely that Bernhard is white. It is highly unlikely that John went to the garden. There is a better than even chance that Julius is a frog.
hypothesis: There is little chance that either 'Julius is a frog' or 'John went to the garden' but not both.
valid_hypothesis: There is a better than even chance that either 'Julius is a frog' or 'John went to the garden' but not both.
invalid_hypothesis: There is little chance that either 'Julius is a frog' or 'John went to the garden' 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.
    0.05::factB.
    0.6::factC.
    
  
    %hop2
    conclusion:-xor(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Julius is a frog' or 'John went to the garden' but not both.