High Compression-Rate Automatic Summarization of Newspaper Articles Based on Combined Use of Significant Sentence Extraction and Sentence Compression

1.在这项工作中，我们使用了一个语料库，其中包含成对的报纸文章和相应的手工简短摘要。这个语料库提供了关于人类如何做简短总结的信息。为了有效地获取这些信息，必须在原句和它的摘要之间进行短语对齐。我们开发了一个利用概念距离和短语间依赖关系的短语对齐器。在研究开始之前，我们使用的是原句集合中依赖距离分布估计的短语间依赖强度。然而，这种方法忽略了原句与其摘要之间的关系。在这项工作中，我们通过原句中存在的具有一定依赖路径长度的短语对的相对频率来估计短语间依赖强度，并且在相应的摘要中仍然具有修饰语-被修饰语关系。主观评价实验结果表明，压缩后的句子质量有了更显著的提高。在本研究采用的短语提取式句子压缩中，原句中不存在修饰语关系的短语有时会在压缩后的句子中出现修饰语关系。这种现象可能会降低压缩句子的可读性。为了提高压缩句子的可读性，我们提出了一种修改修饰语结尾的方法。主观评价实验结果表明了该方法的有效性。我们在概率框架中重新制定了句子压缩方法。在计算由原始句子生成压缩句子的概率时，会出现类似短语重要性和短语间依赖的量，这些量可以从训练语料库中估计出来。结果表明，这种概率方法达到了与我们以前的启发式方法相当的性能。少

1.In this work, we use a corpus in which pairs of newspaper articles and corresponding hand-made short summaries are contained. This corpus provides information about how humans make short summaries. To obtain such information effectively, phrase alignment is necessary between the original sentence and its summary. We developed a phrase aligner that makes use of conceptual distance and inter-phrase dependency.2.Before the research period started, we were using the inter-phrase dependency strength estimated from the distribution of dependency distance in the set of original sentences. This method misses, however, the relationship between the original sentence and its summary. In this work, we estimated the inter-phrase dependency strength from the relative frequency of phrase pairs that exist in the original sentence with a certain dependency path length and remain having modifier-modified relation in the corresponding summary. The result of a subjective evaluation experiment showed sig … More nificant improvement in the quality of compressed sentences.3.In the phrase extraction type sentence compression, which is employed in this research, phrases that are not in modifier-modified relation in the original sentence sometimes appear to have modifier-modified relation in the compressed sentence. Such a phenomenon may degrade the readability of compressed sentences. We worked out a method to modify the phrase ending of the modifier-phrase for improving the readability of compressed sentences. The result of subjective evaluation experiment showed the effectiveness of the method.4.We reformulated our sentence compression method in a probabilistic framework. In calculating the probability that a compressed sentence is generated from an original sentence, quantities similar to phrase significance and inter-phrase dependency appear, which can be estimated from a training corpus. It was shown that this probabilistic approach attains comparable performance as our former, heuristic approach. Less