Possible extensions for Query-based single document summarization

Given a single document summarizer as detailed in this paper, the possible extensions are:
(1) Use a Maximal Marginal Relevance scoring system for ensuring the sentence does not overlap too much with the already extracted sentences. This scoring function would be used for Content selection.
This scoring approach makes sense for a multi-document scenario - I'm not too sure how it helps in a single document scenario. See: "Multi-document summarization by sentence extraction"