  Most extractive summarization methods focus on the main body of the document
from which sentences need to be extracted. However, the gist of the document
may lie in side information, such as the title and image captions which are
often available for newswire articles. We propose to explore side information
in the context of single-document extractive summarization. We develop a
framework for single-document summarization composed of a hierarchical document
encoder and an attention-based extractor with attention over side information.
We evaluate our model on a large scale news dataset. We show that extractive
summarization with side information consistently outperforms its counterpart
that does not use any side information, in terms of both informativeness and
fluency.
