1,187 research outputs found
Beyond Stemming and Lemmatization: Ultra-stemming to Improve Automatic Text Summarization
In Automatic Text Summarization, preprocessing is an important phase to
reduce the space of textual representation. Classically, stemming and
lemmatization have been widely used for normalizing words. However, even using
normalization on large texts, the curse of dimensionality can disturb the
performance of summarizers. This paper describes a new method for normalization
of words to further reduce the space of representation. We propose to reduce
each word to its initial letters, as a form of Ultra-stemming. The results show
that Ultra-stemming not only preserve the content of summaries produced by this
representation, but often the performances of the systems can be dramatically
improved. Summaries on trilingual corpora were evaluated automatically with
Fresa. Results confirm an increase in the performance, regardless of summarizer
system used.Comment: 22 pages, 12 figures, 9 table
SUPERT: Towards New Frontiers in Unsupervised Evaluation Metrics for Multi-Document Summarization
We study unsupervised multi-document summarization evaluation metrics, which
require neither human-written reference summaries nor human annotations (e.g.
preferences, ratings, etc.). We propose SUPERT, which rates the quality of a
summary by measuring its semantic similarity with a pseudo reference summary,
i.e. selected salient sentences from the source documents, using contextualized
embeddings and soft token alignment techniques. Compared to the
state-of-the-art unsupervised evaluation metrics, SUPERT correlates better with
human ratings by 18-39%. Furthermore, we use SUPERT as rewards to guide a
neural-based reinforcement learning summarizer, yielding favorable performance
compared to the state-of-the-art unsupervised summarizers. All source code is
available at https://github.com/yg211/acl20-ref-free-eval.Comment: ACL 202
Detecting (Un)Important Content for Single-Document News Summarization
We present a robust approach for detecting intrinsic sentence importance in
news, by training on two corpora of document-summary pairs. When used for
single-document summarization, our approach, combined with the "beginning of
document" heuristic, outperforms a state-of-the-art summarizer and the
beginning-of-article baseline in both automatic and manual evaluations. These
results represent an important advance because in the absence of cross-document
repetition, single document summarizers for news have not been able to
consistently outperform the strong beginning-of-article baseline.Comment: Accepted By EACL 201
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