Improving Unsupervised Extractive Summarization with Facet-Aware Modeling

Unsupervised extractive summarization aims to extract salient sentences from documents without labeled corpus. Existing methods are mostly graph-based by computing sentence centrality. These methods usually tend to select sentences within the same facet, however, which often leads to the facet bias problem especially when the document has multiple facets (i.e. long-document and multi-documents). To address this problem, we proposed a novel facet-aware centrality-based ranking model. We let the model pay more attention to different facets by introducing a sentence-document weight. The weight is added to the sentence centrality score. We evaluate our method on a wide range of summarization tasks that include 8 representative benchmark datasets. Experimental results show that our method consistently outperforms strong baselines especially in long- and multi-document scenarios and even performs comparably to some supervised models. Extensive analyses confirm that the performance gains come from alleviating the facet bias problem.