Summarization based on bi-directional citation analysis

• We extend citation-based summarization techniques to use both cited and citing documents.
• Our method combines citation text with other elements of cited and citing documents, such as the full text and catchphrases.
• We investigate using citations to extract information from the target document.
• We apply these techniques on the domain of legal judgements, a new area for citations-based summarization.
• On a legal summarization corpus, our methods outperform competitive baselines.

Automatic document summarization using citations is based on summarizing what others explicitly say about the document, by extracting a summary from text around the citations (citances). While this technique works quite well for summarizing the impact of scientific articles, other genres of documents as well as other types of summaries require different approaches. In this paper, we introduce a new family of methods that we developed for legal documents summarization to generate catchphrases for legal cases (where catchphrases are a form of legal summary). Our methods use both incoming and outgoing citations, and we show how citances can be combined with other elements of cited and citing documents, including the full text of the target document, and catchphrases of cited and citing cases. On a legal summarization corpus, our methods outperform competitive baselines. The combination of full text sentences and catchphrases from cited and citing cases is particularly successful. We also apply and evaluate the methods on scientific paper summarization, where they perform at the level of state-of-the-art techniques. Our family of citation-based summarization methods is powerful and flexible enough to target successfully a range of different domains and summarization tasks.