2. The information processing apparatus according to claim 1 , wherein the CPU is further configured to: extract a fourth information element that is directly associated with a particular information element; and extract a fifth information element as the response addition information, wherein the fifth information element having a particular relationship with the extracted fourth information element.
1. An information processing apparatus, comprising: at least one sensor configured to acquire environmental information; a microphone configured to acquire a first sound signal of a user; and a Central Processing Unit (CPU) configured to: store, in a storage apparatus, knowledge information comprising a plurality of information elements, relationship information, and the acquired environmental information, wherein the plurality of information elements include information relating to the user, and wherein the relationship information indicates relationship among the plurality of information elements; convert, based on sound recognition, the acquired first sound signal into text information; detect a question corresponding to the first sound signal based on the text information; detect, based on morphological analysis, intention of the detected question; generate a graphical structure that indicates linkage among a first group of information elements, based on the detected intention of the question, wherein each of a plurality of nodes of the graphical structure corresponds to one of the first group of information elements, and wherein corresponding score associated with each of arcs between at least two of the plurality of nodes is set in advance; extract response basic information which is a response to the detected question and response addition information, based on the generated graphical structure and the acquired environmental information, wherein the response addition information has relationship with the response basic information based on the stored knowledge information, wherein the response addition information is extracted from a second group of information elements included in the first group of information elements having relationship with a first information element extracted as the response basic information and a second information element included in the knowledge information relating to the user, based on at least one information element from the plurality of information elements, wherein the at least one information element from the second group of information elements is selected based on strength of relationship between each of the plurality of information elements and the second information element included in the knowledge information relating to the user, and wherein the second group of information elements lacks relationship with a third information element corresponding to the question; output, based on sound synthesis, the extracted response basic information and the extracted response addition information as a second sound signal; and update the corresponding score based on a user feedback on the outputted second sound signal.