SCMGR: Using Social Context and Multi-Granularity Relations for Unsupervised Social Summarization

Social summarization aims to produce a concise summary that describes the core content of a collection of posts on a specific topic. Existing methods tend to produce sparse or ambiguous representations of posts due to only using short and informal text content. Latest researches use social relations to improve diversity of summaries, yet they model social relations as a regularization item, which has poor flexibility and generalization. Those methods could not embody the deep semantic and social interactions among posts, making summaries still suffer from redundancy. We propose to use Social Context and Multi-Granularity Relations (SCMGR) to improve unsupervised social summarization. It learns more informative representations of posts considering both text semantics and social structure information without any annotated data. First, we design two sociologically motivated meta-paths to construct a social context graph among posts, and adopt a graph convolutional network to aggregate social context information from neighbors. Second, we design a multi-granularity relation decoder to capture the deeper semantic and social interactions from post-word and post-post aspects respectively, which can provide guidance for summary selection from semantic and social structure perspectives. Finally, a sparse reconstruction-based extractor is used to select posts that can best reconstruct original content and social network structure as summaries. Our approach improves the coverage and diversity of summaries. Experimental results on both English and Chinese corpora prove the effectiveness of our model.