Theme recognition in document collections.

为了提高检索效率，人们研究了许多不同的方法来聚类文档集。不幸的是，这些系统通常无法提供改进的检索能力。问题的一部分显然是这样一个事实，即一份给定的文件往往涉及一个以上的主题，因此不可能在排除其他主题的情况下将文件明确地分类为明确的类别。为了克服这个问题，我们开发了旨在从一组文档中确定主题的方法。主题不需要包括任何文件的全部内容。它只需要存在于文档的某个子集中就可以被识别。其中一些相同的文件可能参与几个主题的定义。寻找主题的方法是基于EM算法，需要一个迭代过程，该过程收敛于主题。该方法已被实施和测试，发现是成功的。已经发表了几篇论文。

Many different methods have been investigated for the purpose of clustering sets of documents with the hope of improving retrieval. Unfortunately these have generally failed to provide improved retrieval capability. Part of the problem is clearly the fact that a given document often involves more than one subject so that it is not possible to make a clean categorization of the documents into definite categories to the exclusion of others. In order to overcome this problem we have developed methods that are designed to identify a theme among a set of documents. The theme need not encompass the whole of any document. It only needs to exist in some subset of the documents in order to be identifiable. Some of these same documents may participate in the definition of several themes. The method of finding themes is based on the EM algorithm and requires an iterative procedure which converges to themes. The method has been implemented and tested and found to be successful. Several papers have been published.