765 research outputs found
Learning to Extract Coherent Summary via Deep Reinforcement Learning
Coherence plays a critical role in producing a high-quality summary from a
document. In recent years, neural extractive summarization is becoming
increasingly attractive. However, most of them ignore the coherence of
summaries when extracting sentences. As an effort towards extracting coherent
summaries, we propose a neural coherence model to capture the cross-sentence
semantic and syntactic coherence patterns. The proposed neural coherence model
obviates the need for feature engineering and can be trained in an end-to-end
fashion using unlabeled data. Empirical results show that the proposed neural
coherence model can efficiently capture the cross-sentence coherence patterns.
Using the combined output of the neural coherence model and ROUGE package as
the reward, we design a reinforcement learning method to train a proposed
neural extractive summarizer which is named Reinforced Neural Extractive
Summarization (RNES) model. The RNES model learns to optimize coherence and
informative importance of the summary simultaneously. Experimental results show
that the proposed RNES outperforms existing baselines and achieves
state-of-the-art performance in term of ROUGE on CNN/Daily Mail dataset. The
qualitative evaluation indicates that summaries produced by RNES are more
coherent and readable.Comment: 8 pages, 1 figure, presented at AAAI-201
Guiding Extractive Summarization with Question-Answering Rewards
Highlighting while reading is a natural behavior for people to track salient
content of a document. It would be desirable to teach an extractive summarizer
to do the same. However, a major obstacle to the development of a supervised
summarizer is the lack of ground-truth. Manual annotation of extraction units
is cost-prohibitive, whereas acquiring labels by automatically aligning human
abstracts and source documents can yield inferior results. In this paper we
describe a novel framework to guide a supervised, extractive summarization
system with question-answering rewards. We argue that quality summaries should
serve as a document surrogate to answer important questions, and such
question-answer pairs can be conveniently obtained from human abstracts. The
system learns to promote summaries that are informative, fluent, and perform
competitively on question-answering. Our results compare favorably with those
reported by strong summarization baselines as evaluated by automatic metrics
and human assessors.Comment: NAACL 201
HIBERT: Document Level Pre-training of Hierarchical Bidirectional Transformers for Document Summarization
Neural extractive summarization models usually employ a hierarchical encoder
for document encoding and they are trained using sentence-level labels, which
are created heuristically using rule-based methods. Training the hierarchical
encoder with these \emph{inaccurate} labels is challenging. Inspired by the
recent work on pre-training transformer sentence encoders
\cite{devlin:2018:arxiv}, we propose {\sc Hibert} (as shorthand for {\bf
HI}erachical {\bf B}idirectional {\bf E}ncoder {\bf R}epresentations from {\bf
T}ransformers) for document encoding and a method to pre-train it using
unlabeled data. We apply the pre-trained {\sc Hibert} to our summarization
model and it outperforms its randomly initialized counterpart by 1.25 ROUGE on
the CNN/Dailymail dataset and by 2.0 ROUGE on a version of New York Times
dataset. We also achieve the state-of-the-art performance on these two
datasets.Comment: to appear in ACL 201
From Standard Summarization to New Tasks and Beyond: Summarization with Manifold Information
Text summarization is the research area aiming at creating a short and
condensed version of the original document, which conveys the main idea of the
document in a few words. This research topic has started to attract the
attention of a large community of researchers, and it is nowadays counted as
one of the most promising research areas. In general, text summarization
algorithms aim at using a plain text document as input and then output a
summary. However, in real-world applications, most of the data is not in a
plain text format. Instead, there is much manifold information to be
summarized, such as the summary for a web page based on a query in the search
engine, extreme long document (e.g., academic paper), dialog history and so on.
In this paper, we focus on the survey of these new summarization tasks and
approaches in the real-world application.Comment: Accepted by IJCAI 2020 Survey Trac
Deep Transfer Reinforcement Learning for Text Summarization
Deep neural networks are data hungry models and thus face difficulties when
attempting to train on small text datasets. Transfer learning is a potential
solution but their effectiveness in the text domain is not as explored as in
areas such as image analysis. In this paper, we study the problem of transfer
learning for text summarization and discuss why existing state-of-the-art
models fail to generalize well on other (unseen) datasets. We propose a
reinforcement learning framework based on a self-critic policy gradient
approach which achieves good generalization and state-of-the-art results on a
variety of datasets. Through an extensive set of experiments, we also show the
ability of our proposed framework to fine-tune the text summarization model
using only a few training samples. To the best of our knowledge, this is the
first work that studies transfer learning in text summarization and provides a
generic solution that works well on unseen data
Reference and Document Aware Semantic Evaluation Methods for Korean Language Summarization
Text summarization refers to the process that generates a shorter form of
text from the source document preserving salient information. Many existing
works for text summarization are generally evaluated by using recall-oriented
understudy for gisting evaluation (ROUGE) scores. However, as ROUGE scores are
computed based on n-gram overlap, they do not reflect semantic meaning
correspondences between generated and reference summaries. Because Korean is an
agglutinative language that combines various morphemes into a word that express
several meanings, ROUGE is not suitable for Korean summarization. In this
paper, we propose evaluation metrics that reflect semantic meanings of a
reference summary and the original document, Reference and Document Aware
Semantic Score (RDASS). We then propose a method for improving the correlation
of the metrics with human judgment. Evaluation results show that the
correlation with human judgment is significantly higher for our evaluation
metrics than for ROUGE scores.Comment: COLING 202
A novel repetition normalized adversarial reward for headline generation
While reinforcement learning can effectively improve language generation
models, it often suffers from generating incoherent and repetitive phrases
\cite{paulus2017deep}. In this paper, we propose a novel repetition normalized
adversarial reward to mitigate these problems. Our repetition penalized reward
can greatly reduce the repetition rate and adversarial training mitigates
generating incoherent phrases. Our model significantly outperforms the baseline
model on ROUGE-1\,(+3.24), ROUGE-L\,(+2.25), and a decreased repetition-rate
(-4.98\%).Comment: Accepted by ICASSP 201
Fast Abstractive Summarization with Reinforce-Selected Sentence Rewriting
Inspired by how humans summarize long documents, we propose an accurate and
fast summarization model that first selects salient sentences and then rewrites
them abstractively (i.e., compresses and paraphrases) to generate a concise
overall summary. We use a novel sentence-level policy gradient method to bridge
the non-differentiable computation between these two neural networks in a
hierarchical way, while maintaining language fluency. Empirically, we achieve
the new state-of-the-art on all metrics (including human evaluation) on the
CNN/Daily Mail dataset, as well as significantly higher abstractiveness scores.
Moreover, by first operating at the sentence-level and then the word-level, we
enable parallel decoding of our neural generative model that results in
substantially faster (10-20x) inference speed as well as 4x faster training
convergence than previous long-paragraph encoder-decoder models. We also
demonstrate the generalization of our model on the test-only DUC-2002 dataset,
where we achieve higher scores than a state-of-the-art model.Comment: ACL 2018 (17 pages
Iterative Document Representation Learning Towards Summarization with Polishing
In this paper, we introduce Iterative Text Summarization (ITS), an
iteration-based model for supervised extractive text summarization, inspired by
the observation that it is often necessary for a human to read an article
multiple times in order to fully understand and summarize its contents. Current
summarization approaches read through a document only once to generate a
document representation, resulting in a sub-optimal representation. To address
this issue we introduce a model which iteratively polishes the document
representation on many passes through the document. As part of our model, we
also introduce a selective reading mechanism that decides more accurately the
extent to which each sentence in the model should be updated. Experimental
results on the CNN/DailyMail and DUC2002 datasets demonstrate that our model
significantly outperforms state-of-the-art extractive systems when evaluated by
machines and by humans.Comment: 10 pages, 4 figures. emnlp 201
A Deep Reinforced Model for Abstractive Summarization
Attentional, RNN-based encoder-decoder models for abstractive summarization
have achieved good performance on short input and output sequences. For longer
documents and summaries however these models often include repetitive and
incoherent phrases. We introduce a neural network model with a novel
intra-attention that attends over the input and continuously generated output
separately, and a new training method that combines standard supervised word
prediction and reinforcement learning (RL). Models trained only with supervised
learning often exhibit "exposure bias" - they assume ground truth is provided
at each step during training. However, when standard word prediction is
combined with the global sequence prediction training of RL the resulting
summaries become more readable. We evaluate this model on the CNN/Daily Mail
and New York Times datasets. Our model obtains a 41.16 ROUGE-1 score on the
CNN/Daily Mail dataset, an improvement over previous state-of-the-art models.
Human evaluation also shows that our model produces higher quality summaries
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