Forst: Question Answering System Using Basic Element at NTCIR-11 QA-Lab Task Kotaro Sakamoto *1, *2 , Hyogo Matsui *1 , Eisuke Matsunaga *1 , Takahisa Jin *1 , Hideyuki Shibuki *1 , Tatsunori Mori *1 , Madoka Ishioroshi *2 , Noriko Kando *2,*3 *1: Yokohama National University, *2: National Institute of Informatics, *3: The Graduate University for Advanced Studies (SOKENDAI) {sakamoto|m_hyogo|shin7240|taka_jin|shib|mori}@forest.eis.ynu.ac.jp, {ishioroshi|kando}@nii.ac.jp ABSTRACT This paper describes Forst's approach to university entrance examinations at NTCIR-11 QA-Lab Task. Our system consists of two types of modules: dedicated modules for each question format and common modules called by the dedicated modules as necessary. Our system uses Basic Element in order to more exactly grasp and reflect the import of questions. We also tackled short-essay questions in the secondary examinations. Team Name Forst Subtask Japanese Keywords question answering, Basic Element, university entrance examination, world history 1. INTRODUCTION Question answering is widely regarded as an advancement in information retrieval. However, QA systems are not as popular as search engines in the real world. In order to apply QA systems to real-world problems we tackle the QA-Lab task dealing with questions from the National Center Test for University Admissions and from the secondary exams at 5 universities in Japan. Most of questions from the university entrance examinations have more complex structure than general QA questions, and require more exact understanding. Figure 1 shows an example question from the Center Test and the question structure. A question roughly consists of four types of descriptions: instruction in part of exam, context, instruction and answer candidates. Context has various expressions: sentence, word, figure, table and so on. Although all questions of the Center Test are multiple choice, the substance has various question: factoid, true-or-false, fill-in-the-blank and so on. In the case of secondary exams, context may be merged into instruction, and answer candidates may not exist. Figure 2 shows an example question from the secondary exam at Tokyo University. This question is a short- essay question, and the context except words, which must be included in the answer essay, is merged into the instruction. To answer such various exam questions, we classify exam questions into several question format types, develop modules dedicated to each question format type. We also use Basic Element[1-2] in order to more exactly grasp the import of question sentence. Basic Element is a minimal semantic unit, which is a dependency between words in a sentence and expressed as a triple (head | modifier | relation). Figure 1: Example of the Center Test question Figure 2: Example of the secondary exam question Proceedings of the 11th NTCIR Conference, December 9-12, 2014, Tokyo, Japan 532