context: We believe that Bernhard is a frog. There is almost no chance that Brian is gray. Chances are slight that Emily is a sheep.
hypothesis: There is little chance that either 'Emily is a sheep' or 'Brian is gray' but not both.
valid_hypothesis: There is little chance that either 'Emily is a sheep' or 'Brian is gray' but not both.
invalid_hypothesis: It is likely that either 'Emily is a sheep' or 'Brian is gray' 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
    0.75::factA.
    0.02::factB.
    0.1::factC.
    
  
    %hop2
    conclusion:-xor(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Emily is a sheep' or 'Brian is gray' but not both.