Recently, domain-specific PLMs have been proposed to boost the task performance of specific domains (e.g., biomedical and computer science) by continuing to pre-train general PLMs with domain-specific corpora. However, this Domain-Adaptive Pre-Training (DAPT; Gururangan et al. (2020)) tends to forget the previous general knowledge acquired by general PLMs, which leads to a catastrophic forgetting phenomenon and sub-optimal performance. To alleviate this problem, we propose a new framework of General Memory Augmented Pre-trained Language Model (G-MAP), which augments the domain-specific PLM by a memory representation built from the frozen general PLM without losing any general knowledge. Specifically, we propose a new memory-augmented layer, and based on it, different augmented strategies are explored to build the memory representation and then adaptively fuse it into the domain-specific PLM. We demonstrate the effectiveness of G-MAP on various domains (biomedical and computer science publications, news, and reviews) and different kinds (text classification, QA, NER) of tasks, and the extensive results show that the proposed G-MAP can achieve SOTA results on all tasks.

预训练的语言模型（PLM）在各种自然语言理解任务上取得了巨大的成功。另一方面，对PLM的简单微调对于特定于领域的任务可能是次优的，因为它们不可能涵盖所有域中的知识。尽管PLM的自适应预培训可以帮助他们获得特定于领域的知识，但需要大量的培训成本。此外，自适应预训练可能会通过造成灾难性忘记其常识来损害PLM在下游任务上的表现。为了克服PLM适应性适应性预训练的这种局限性，我们提出了一个新颖的域名适应框架，用于将PLMS创造为知识增强语言模型适应性（KALA），该框架调节了PLM的中间隐藏表示与域中的中间隐藏表示，由实体和实体和实体和实体和实体构成他们的关系事实。我们验证了Kala在问题答案中的性能，并在各个域的多个数据集上命名实体识别任务。结果表明，尽管在计算上有效，但我们的Kala在很大程度上优于适应性预训练。代码可在以下网址获得：https：//github.com/nardien/kala/。

Language model pre-training has proven to be useful in learning universal language representations. As a state-of-the-art language model pre-training model, BERT (Bidirectional Encoder Representations from Transformers) has achieved amazing results in many language understanding tasks. In this paper, we conduct exhaustive experiments to investigate different fine-tuning methods of BERT on text classification task and provide a general solution for BERT fine-tuning. Finally, the proposed solution obtains new state-of-the-art results on eight widely-studied text classification datasets. 1

由于表现强劲，预用的语言模型已成为许多NLP任务的标准方法，但他们培训价格昂贵。我们提出了一个简单高效的学习框架TLM，不依赖于大规模预制。给定一些标记的任务数据和大型常规语料库，TLM使用任务数据作为查询来检索一般语料库的微小子集，并联合优化任务目标和从头开始的语言建模目标。在四个域中的八个分类数据集上，TLM实现了比预用语言模型（例如Roberta-Light）更好地或类似的结果，同时减少了两个数量级的训练拖鞋。高精度和效率，我们希望TLM将有助于民主化NLP并加快发展。

语言模型是使用大量通用数据（如Book Copus，Common Crawl和Wikipedia）进行预训练的，这对于模型了解语言的语言特征至关重要。新的研究建议将域自适应预训练（DAPT）和任务自适应预训练（TAPT）作为最终填充任务之前的中间步骤。此步骤有助于涵盖目标域词汇，并改善下游任务的模型性能。在这项工作中，我们仅研究训练在TAPT和特定于任务的填充过程中嵌入层对模型性能的影响。基于我们的研究，我们提出了一种简单的方法，以通过对BERT层进行选择性预训练，使基于BERT的模型的中间步骤更有效。我们表明，在TAPT期间仅训练BERT嵌入层足以适应目标域的词汇并实现可比的性能。我们的方法在计算上是有效的，在TAPT期间训练了78％的参数。所提出的嵌入层列式方法也可以是一种有效的域适应技术。

Neural models that do not rely on pre-training have excelled in the keyphrase generation task with large annotated datasets. Meanwhile, new approaches have incorporated pre-trained language models (PLMs) for their data efficiency. However, there lacks a systematic study of how the two types of approaches compare and how different design choices can affect the performance of PLM-based models. To fill in this knowledge gap and facilitate a more informed use of PLMs for keyphrase extraction and keyphrase generation, we present an in-depth empirical study. Formulating keyphrase extraction as sequence labeling and keyphrase generation as sequence-to-sequence generation, we perform extensive experiments in three domains. After showing that PLMs have competitive high-resource performance and state-of-the-art low-resource performance, we investigate important design choices including in-domain PLMs, PLMs with different pre-training objectives, using PLMs with a parameter budget, and different formulations for present keyphrases. Further results show that (1) in-domain BERT-like PLMs can be used to build strong and data-efficient keyphrase generation models; (2) with a fixed parameter budget, prioritizing model depth over width and allocating more layers in the encoder leads to better encoder-decoder models; and (3) introducing four in-domain PLMs, we achieve a competitive performance in the news domain and the state-of-the-art performance in the scientific domain.

GPT-2和BERT展示了在各种自然语言处理任务上使用预训练的语言模型（LMS）的有效性。但是，在应用于资源丰富的任务时，LM微调通常会遭受灾难性的遗忘。在这项工作中，我们引入了一个协同的培训框架（CTNMT），该框架是将预训练的LMS集成到神经机器翻译（NMT）的关键。我们提出的CTNMT包括三种技术：a）渐近蒸馏，以确保NMT模型可以保留先前的预训练知识； b）动态的开关门，以避免灾难性忘记预训练的知识； c）根据计划的政策调整学习步伐的策略。我们在机器翻译中的实验表明，WMT14英语 - 德语对的CTNMT获得了最高3个BLEU得分，甚至超过了先前的最先进的预培训辅助NMT NMT的NMT。尽管对于大型WMT14英语法国任务，有400万句话，但我们的基本模型仍然可以显着改善最先进的变压器大型模型，超过1个BLEU得分。代码和模型可以从https://github.com/bytedance/neurst/tree/Master/Master/examples/ctnmt下载。

Language models with the Transformers structure have shown great performance in natural language processing. However, there still poses problems when fine-tuning pre-trained language models on downstream tasks, such as over-fitting or representation collapse. In this work, we propose HyPe, a simple yet effective fine-tuning technique to alleviate such problems by perturbing hidden representations of Transformers layers. Unlike previous works that only add noise to inputs or parameters, we argue that the hidden representations of Transformers layers convey more diverse and meaningful language information. Therefore, making the Transformers layers more robust to hidden representation perturbations can further benefit the fine-tuning of PLMs en bloc. We conduct extensive experiments and analyses on GLUE and other natural language inference datasets. Results demonstrate that HyPe outperforms vanilla fine-tuning and enhances generalization of hidden representations from different layers. In addition, HyPe acquires negligible computational overheads, and is better than and compatible with previous state-of-the-art fine-tuning techniques.

We introduce a new language representation model called BERT, which stands for Bidirectional Encoder Representations from Transformers. Unlike recent language representation models (Peters et al., 2018a;Radford et al., 2018), BERT is designed to pretrain deep bidirectional representations from unlabeled text by jointly conditioning on both left and right context in all layers. As a result, the pre-trained BERT model can be finetuned with just one additional output layer to create state-of-the-art models for a wide range of tasks, such as question answering and language inference, without substantial taskspecific architecture modifications.BERT is conceptually simple and empirically powerful. It obtains new state-of-the-art results on eleven natural language processing tasks, including pushing the GLUE score to 80.5% (7.7% point absolute improvement), MultiNLI accuracy to 86.7% (4.6% absolute improvement), SQuAD v1.1 question answering Test F1 to 93.2 (1.5 point absolute improvement) and SQuAD v2.0 Test F1 to 83.1 (5.1 point absolute improvement).

当前的预训练语言模型（PLM）通常是通过静态数据训练的，忽略了在现实情况下，各种来源的流数据可能会不断增长。这要求PLM终生整合来自所有来源的信息。尽管可以通过对所有现有数据进行详尽的预培训来实现此目标，但已知该过程在计算上是昂贵的。为此，我们提出了Elle，目的是为新兴数据有效终身预训练。具体而言，ELLE由（1）函数保留的模型扩展组成，它们灵活地扩展了现有的PLM的宽度和深度以提高知识获取的效率； （2）预先训练的领域提示，它消除了在预训练期间学习的多功能知识，并刺激了下游任务的适当知识。我们通过来自BERT和GPT上5个域的流数据进行实验。结果表明，在预训练效率和下游性能中，ELLE的优越性超过了各种终身学习基线。这些代码可在https://github.com/thunlp/elle上公开获得。

尽管预训练的语言模型（PLM）已经在各种自然语言处理（NLP）任务上实现了最先进的表现，但在处理知识驱动的任务时，它们被证明缺乏知识。尽管为PLM注入知识做出了许多努力，但此问题仍然开放。为了应对挑战，我们提出\ textbf {dictbert}，这是一种具有词典知识增强PLM的新方法，比知识图（kg）更容易获取。在预训练期间，我们通过对比度学习将两个新颖的预训练任务注入plms：\ textit {dictionary输入预测}和\ textit {entriT {输入描述歧视}。在微调中，我们使用预先训练的dictbert作为插件知识库（KB）来检索输入序列中确定的条目的隐式知识，并将检索到的知识注入输入中，以通过新颖的额外跳动来增强其表示形式注意机制。我们评估了我们的方法，包括各种知识驱动和语言理解任务，包括NER，关系提取，CommonSenseQA，OpenBookQa和Glue。实验结果表明，我们的模型可以显着改善典型的PLM：它的大幅提高了0.5 \％，2.9 \％，9.0 \％，7.1 \％\％和3.3 \％，分别对Roberta--也有效大的。

Language models pretrained on text from a wide variety of sources form the foundation of today's NLP. In light of the success of these broad-coverage models, we investigate whether it is still helpful to tailor a pretrained model to the domain of a target task. We present a study across four domains (biomedical and computer science publications, news, and reviews) and eight classification tasks, showing that a second phase of pretraining indomain (domain-adaptive pretraining) leads to performance gains, under both high-and low-resource settings. Moreover, adapting to the task's unlabeled data (task-adaptive pretraining) improves performance even after domain-adaptive pretraining. Finally, we show that adapting to a task corpus augmented using simple data selection strategies is an effective alternative, especially when resources for domain-adaptive pretraining might be unavailable. Overall, we consistently find that multiphase adaptive pretraining offers large gains in task performance.

在这项工作中，我们探索如何学习专用的语言模型，旨在学习从文本文件中学习关键词的丰富表示。我们在判别和生成设置中进行预训练变压器语言模型（LMS）的不同掩蔽策略。在歧视性设定中，我们引入了一种新的预训练目标 - 关键边界，用替换（kbir）infifiling，在使用Kbir预先训练的LM进行微调时显示出在Sota上的性能（F1中高达9.26点）的大量增益关键酶提取的任务。在生成设置中，我们为BART - 键盘介绍了一个新的预训练设置，可再现与CATSeq格式中的输入文本相关的关键字，而不是Denoised原始输入。这也导致在关键词中的性能（F1 @ M）中的性能（高达4.33点），用于关键正版生成。此外，我们还微调了在命名实体识别（ner），问题应答（qa），关系提取（重新），抽象摘要和达到与SOTA的可比性表现的预训练的语言模型，表明学习丰富的代表关键词确实有利于许多其他基本的NLP任务。

事实证明，将先验知识纳入预训练的语言模型中对知识驱动的NLP任务有效，例如实体键入和关系提取。当前的培训程序通常通过使用知识掩盖，知识融合和知识更换将外部知识注入模型。但是，输入句子中包含的事实信息尚未完全开采，并且尚未严格检查注射的外部知识。结果，无法完全利用上下文信息，并将引入额外的噪音，或者注入的知识量受到限制。为了解决这些问题，我们提出了MLRIP，该MLRIP修改了Ernie-Baidu提出的知识掩盖策略，并引入了两阶段的实体替代策略。进行全面分析的广泛实验说明了MLRIP在军事知识驱动的NLP任务中基于BERT的模型的优势。

将电子健康记录（EHR）自动分为诊断代码对NLP社区的挑战。最先进的方法将此问题视为多标签分类问题，并提出了各种架构来对此问题进行建模。但是，这些系统并未利用验证的语言模型的出色性能，这在自然语言理解任务上实现了出色的性能。先前的工作表明，经常使用的填充方案在此任务上表现不佳。因此，本文旨在分析表现不佳的原因，并通过验证的语言模型为自动编码开发一个框架。我们通过实验发现了三个主要问题：1）大标签空间，2）长输入序列和3）域预读和微调之间的域不匹配。我们提出了PLMICD，该框架通过各种策略来应对挑战。实验结果表明，我们提出的框架可以在基准模拟数据上以多个指标来克服挑战和实现最新性能。源代码可从https://github.com/miulab/plm-icd获得

Although pre-trained language models (PLMs) have shown impressive performance by text-only self-supervised training, they are found lack of visual semantics or commonsense, e.g., sizes, shapes, and colors of commonplace objects. Existing solutions often rely on explicit images for visual knowledge augmentation (requiring time-consuming retrieval or generation), and they also conduct the augmentation for the whole input text, without considering whether it is actually needed in specific inputs or tasks. To address these issues, we propose a novel visually-augmented fine-tuning approach that can be generally applied to various PLMs or NLP tasks, without using any retrieved or generated images, namely VAWI. Specifically, we first identify the visually-hungry words (VH-words) from input text via a token selector, where three different methods have been proposed, including syntax-, attention- and learning-based strategies. Then, we adopt a fixed CLIP text encoder to generate the visually-augmented representations of these VH-words. As it has been pre-trained by vision-language alignment task on the large-scale corpus, it is capable of injecting visual semantics into the aligned text representations. Finally, the visually-augmented features will be fused and transformed into the pre-designed visual prompts based on VH-words, which can be inserted into PLMs to enrich the visual semantics in word representations. We conduct extensive experiments on ten NLP tasks, i.e., GLUE benchmark, CommonsenseQA, CommonGen, and SNLI-VE. Experimental results show that our approach can consistently improve the performance of BERT, RoBERTa, BART, and T5 at different scales, and outperform several competitive baselines significantly. Our codes and data are publicly available at~\url{https://github.com/RUCAIBox/VAWI}.

Natural Language Processing (NLP) has been revolutionized by the use of Pre-trained Language Models (PLMs) such as BERT. Despite setting new records in nearly every NLP task, PLMs still face a number of challenges including poor interpretability, weak reasoning capability, and the need for a lot of expensive annotated data when applied to downstream tasks. By integrating external knowledge into PLMs, \textit{\underline{K}nowledge-\underline{E}nhanced \underline{P}re-trained \underline{L}anguage \underline{M}odels} (KEPLMs) have the potential to overcome the above-mentioned limitations. In this paper, we examine KEPLMs systematically through a series of studies. Specifically, we outline the common types and different formats of knowledge to be integrated into KEPLMs, detail the existing methods for building and evaluating KEPLMS, present the applications of KEPLMs in downstream tasks, and discuss the future research directions. Researchers will benefit from this survey by gaining a quick and comprehensive overview of the latest developments in this field.

预先接受的语言模型实现了最先进的导致各种自然语言处理（NLP）任务。 GPT-3表明，缩放预先训练的语言模型可以进一步利用它们的巨大潜力。最近提出了一个名为Ernie 3.0的统一框架，以预先培训大型知识增强型号，并培训了具有10亿参数的模型。 Ernie 3.0在各种NLP任务上表现出最先进的模型。为了探讨缩放的表现，我们培养了百卢比的3.0泰坦参数型号，在PaddlePaddle平台上有高达260亿参数的泰坦。此外，我们设计了一种自我监督的对抗性损失和可控语言建模损失，以使ERNIE 3.0 TITAN产生可信和可控的文本。为了减少计算开销和碳排放，我们向Ernie 3.0泰坦提出了一个在线蒸馏框架，教师模型将同时教授学生和培训。埃塞尼3.0泰坦是迄今为止最大的中国密集预训练模型。经验结果表明，Ernie 3.0泰坦在68个NLP数据集中优于最先进的模型。

Pre-trained Language Models (PLMs) which are trained on large text corpus through the self-supervised learning method, have yielded promising performance on various tasks in Natural Language Processing (NLP). However, though PLMs with huge parameters can effectively possess rich knowledge learned from massive training text and benefit downstream tasks at the fine-tuning stage, they still have some limitations such as poor reasoning ability due to the lack of external knowledge. Incorporating knowledge into PLMs has been tried to tackle these issues. In this paper, we present a comprehensive review of Knowledge-Enhanced Pre-trained Language Models (KE-PLMs) to provide a clear insight into this thriving field. We introduce appropriate taxonomies respectively for Natural Language Understanding (NLU) and Natural Language Generation (NLG) to highlight the focus of these two kinds of tasks. For NLU, we take several types of knowledge into account and divide them into four categories: linguistic knowledge, text knowledge, knowledge graph (KG), and rule knowledge. The KE-PLMs for NLG are categorized into KG-based and retrieval-based methods. Finally, we point out some promising future directions of KE-PLMs.

We present Pre-trained Machine Reader (PMR), a novel method to retrofit Pre-trained Language Models (PLMs) into Machine Reading Comprehension (MRC) models without acquiring labeled data. PMR is capable of resolving the discrepancy between model pre-training and downstream fine-tuning of existing PLMs, and provides a unified solver for tackling various extraction tasks. To achieve this, we construct a large volume of general-purpose and high-quality MRC-style training data with the help of Wikipedia hyperlinks and design a Wiki Anchor Extraction task to guide the MRC-style pre-training process. Although conceptually simple, PMR is particularly effective in solving extraction tasks including Extractive Question Answering and Named Entity Recognition, where it shows tremendous improvements over previous approaches especially under low-resource settings. Moreover, viewing sequence classification task as a special case of extraction task in our MRC formulation, PMR is even capable to extract high-quality rationales to explain the classification process, providing more explainability of the predictions.