Improvement of accuracy of question-answering based on question reformulation

本研究最初旨在提高列表型问答的准确性。列表式问答是系统要求列举给定问题的所有正确答案的任务。在我们提出的方法中，我们利用现有问答系统给出的分数分布来回答候选人。首先，我们假设分布是两个分布的混合，即一个是正确答案，另一个是错误答案。其次，我们还假设这两个分布都是正态分布。在这些假设下，我们提出了一种利用EM算法从混合分布中分离正确答案的方法。另一方面，这两种分布的边界有时可能不清晰，因为有可能问答系统无法产生适当的分数。在这种情况下，我们根据每个答案候选人与知识源中问题句子的关键词的共现性…More重新计算分数。实验结果表明，分数分布在列表型问答中的应用是有效的。然而，基于共现的分数重新计算并不有效。因此，我们还研究了一种基于上述发现的方法，即两个分布边界的明显程度表明系统为给定问题找到的答案候选人的适当性。我们将“问题重新表述”的概念概括如下。我们通过对原始问题应用几种可能的解释来生成一组候选问题。在这种情况下，可以通过选择合适的问题候选人和他们的答案候选人来实现问题的重新制定。例如，当我们将问题重组应用于上下文问答时，可能会提高问答的准确性。该概念也可用于提高跨语言问答的准确性。少

This research originally aimed at the improvement of accuracy of list-type question answering. The list-type question-answering is the task in which a system requested to enumerate all correct answers to a given question. In our proposed method, we utilize the distribution of the score that an existing question answering system gives to answer candidates. First we assume that the distribution is a mixture of two distributions, i.e., one of the correct answers and one of the incorrect answers. Second we also suppose that each of the two distributions is a normal distribution. Under these assumptions, we proposed a method to separate the correct answers from the mixture of the distributions by using the EM algorithm. On the other hand, the boundary of the two distributions may be occasionally indistinct because there is a possibility that the question-answering system fails to produce appropriate scores. In such a case, we perform a re-calculation of scores according to the co-occurrence … More of each answer candidate and the keywords of the question sentence in the knowledge source.The experimental results show that the utilization of the score distribution is effective for the list-type question-answering. However, the re-calculation of scores based on the co-occurrence does not work effectively.Therefore, we also investigated a method based on the above findings, that is, the degree of distinctness of the two distributions' boundaries indicates the appropriateness of answer candidates that are found by the system for a given question. We generalized the notion of "question reformulation" as follows. We generate a set of question candidates by applying several possible interpretations to the original question. In this situation, the question reformulation can be achieved by selecting appropriate question candidates and their answer candidates.For example, when we applied the question reformulation to contextual question-answering, the accuracy of question answering may be improved. The notion also can be used for the improvement of accuracy of cross-lingual question answering. Less