Step 2: Selection of best nuggets Redundancy is a more severe issue in MDS (Goldstein et al., 2000b;Goldstein et al., 2000a) compared to single-document summarization, as recurring facts are more likely to occur in multiple different documents about the same topic than within a single one.
we ask the annotators to group the selected nuggets from step 1 if they "convey the same meaning using different wording" (Bhagat and Hovy, 2013, p. 463).