System and method for answering natural language question

A system for answering a natural language question, the system comprising:

• one or more processors that process computer executable program code embodied in non-transitory computer readable storage media,
• wherein when the program code is executed by computer the program code causes the processor to perform the steps of:
• analyzing text of irregular documents stored in a storage unit, classifying and indexing the irregular documents according to meanings of sentences or paragraphs, and stores in a database the irregular documents indexed according to the meanings by the index unit, wherein the sentences or the paragraphs in the irregular documents are classified based on structural information or results of understanding a natural language;
• extracting an index word by semantically analyzing an input question, and searches the database for documents related to the extracted index word;
• and
• generating a correct answer to the question by analyzing the documents searched by the retrieval unit, and provides results of the search and the generated correct answer,
• wherein analyzing the text of the stored irregular documents comprises analyzing by a document analyzer the text of the stored irregular documents;
• wherein the classifying comprises receiving by a semantic analyzer text analyzed by the document analyzer and classifying the meanings of the received text in units of sentences or paragraphs by a semantic classifier;
• and
• wherein the indexing comprises indexing by a document indexer sentences or paragraphs classified by the semantic classifier according to the meanings in units of morphemes, entity names, phrases, syntax structures, semantic structures, sentence structures, “subject-verb” structures, “object-verb” structures, and “subject-verb-object” structures.