15. The apparatus of claim 10 , wherein selecting at least one candidate answer in the set of candidate answers as an answer for the input question based on the user input comprises: updating the set of candidate answers based on the user input; and selecting the at least one candidate answer from the updated set of candidate answers.
15. The apparatus of claim 10 , wherein selecting at least one candidate answer in the set of candidate answers as an answer for the input question based on the user input comprises: updating the set of candidate answers based on the user input; and selecting the at least one candidate answer from the updated set of candidate answers. 16. The apparatus of claim 15 , wherein updating the set of candidate answers comprises modifying confidence scores associated with one or more of the candidate answers in the set of candidate answers based on the user input, wherein confidence scores for candidate answers having evidence passages corresponding to the user input are increased and candidate answers having evidence passages not corresponding to the user input are decreased.