Recently, compressive text summarisation offers a balance between the
conciseness issue of extractive summarisation and the factual hallucination
issue of abstractive summarisation. However, most existing compressive
summarisation methods are supervised, relying on the expensive effort of
creating a new training dataset with corresponding compressive summaries. In
this paper, we propose an efficient and interpretable compressive summarisation
method that utilises unsupervised dual-agent reinforcement learning to optimise
a summary's semantic coverage and fluency by simulating human judgment on
summarisation quality. Our model consists of an extractor agent and a
compressor agent, and both agents have a multi-head attentional pointer-based
structure. The extractor agent first chooses salient sentences from a document,
and then the compressor agent compresses these extracted sentences by selecting
salient words to form a summary without using reference summaries to compute
the summary reward. To our best knowledge, this is the first work on
unsupervised compressive summarisation. Experimental results on three widely
used datasets (e.g., Newsroom, CNN/DM, and XSum) show that our model achieves
promising performance and a significant improvement on Newsroom in terms of the
ROUGE metric, as well as interpretability of semantic coverage of summarisation
results.

提出了一种利用无监督双代理强化学习来优化摘要语义覆盖和流畅度的高效且可解释的压缩摘要方法，该模型由提取器代理和压缩器代理组成，并且两个代理都具有多头注意力指针结构。实验结果表明，该模型在广泛使用的三个数据集上均取得了有希望的表现。