context: Chances are slight that Greg is yellow. There is a very good chance that Winona is a mouse. There is a better than even chance that John took the football.
hypothesis: It is impossible that either 'Winona is a mouse' or 'John took the football' but not both.
valid_hypothesis: Chances are about even that either 'Winona is a mouse' or 'John took the football' but not both.
invalid_hypothesis: It is impossible that either 'Winona is a mouse' or 'John took the football' 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.
    0.8::factB.
    0.6::factC.
    
  
    %hop2
    conclusion:-xor(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Winona is a mouse' or 'John took the football' but not both.