Since we attempt to summarize reviews, we assume that a good summary must involve as many sentiments as possible.
we define the informativeness score as follows: where e indicates sentiment e = a, p as the tuple of aspect a and polarity p = {−1, 0, 1}, E(S) is the set of sentiments contained S, and f (e) is the score of sentiment e. Aspect a represents a standpoint for evaluating products and services.