基于方面的情感分析（ABSA）是一项精细的情感分析任务，它的重点是检测句子中的情感极性。但是，它始终对多方面的挑战敏感，在句子中，多个方面的特征将相互影响。为了减轻此问题，我们设计了一个新颖的培训框架，称为对比度跨通道数据增强（C3 DA），该框架利用了一个内域的发电机来构建更多的多种相应样本，然后通过对比度模型通过对比度学习的稳健性，从而通过对比度学习的稳健性这些生成的数据。实际上，鉴于生成预审预测的语言模型和一些有限的ABSA标记数据，我们首先采用一些参数效率的方法来执行内域微调。然后，所获得的内域发生器用于从两个通道（即方面增强通道和极性增强通道）生成合成句子，该句子分别在给定的方面和极性上生成句子条件。具体而言，我们的C3 DA以跨渠道的方式执行句子生成以获取更多句子，并提出了熵最小化过滤器以滤除低质量生成的样品。广泛的实验表明，我们的C3 DA可以在准确性和宏观上胜过约1％的基准，而不会增加1％。代码和数据在https://github.com/wangbing1416/c3da中发布。

Controllable Text Generation (CTG) is emerging area in the field of natural language generation (NLG). It is regarded as crucial for the development of advanced text generation technologies that are more natural and better meet the specific constraints in practical applications. In recent years, methods using large-scale pre-trained language models (PLMs), in particular the widely used transformer-based PLMs, have become a new paradigm of NLG, allowing generation of more diverse and fluent text. However, due to the lower level of interpretability of deep neural networks, the controllability of these methods need to be guaranteed. To this end, controllable text generation using transformer-based PLMs has become a rapidly growing yet challenging new research hotspot. A diverse range of approaches have emerged in the recent 3-4 years, targeting different CTG tasks which may require different types of controlled constraints. In this paper, we present a systematic critical review on the common tasks, main approaches and evaluation methods in this area. Finally, we discuss the challenges that the field is facing, and put forward various promising future directions. To the best of our knowledge, this is the first survey paper to summarize CTG techniques from the perspective of PLMs. We hope it can help researchers in related fields to quickly track the academic frontier, providing them with a landscape of the area and a roadmap for future research.

Sequence-to-sequence (seq2seq) learning is a popular fashion for large-scale pretraining language models. However, the prior seq2seq pretraining models generally focus on reconstructive objectives on the decoder side and neglect the effect of encoder-side supervision, which we argue may lead to sub-optimal performance. To verify our hypothesis, we first empirically study the functionalities of the encoder and decoder in seq2seq pretrained language models, and find that the encoder takes an important but under-exploitation role than the decoder regarding the downstream performance and neuron activation. Therefore, we propose an encoding-enhanced seq2seq pretraining strategy, namely E2S2, which improves the seq2seq models via integrating more efficient self-supervised information into the encoders. Specifically, E2S2 adopts two self-supervised objectives on the encoder side from two aspects: 1) locally denoising the corrupted sentence (denoising objective); and 2) globally learning better sentence representations (contrastive objective). With the help of both objectives, the encoder can effectively distinguish the noise tokens and capture high-level (i.e. syntactic and semantic) knowledge, thus strengthening the ability of seq2seq model to accurately achieve the conditional generation. On a large diversity of downstream natural language understanding and generation tasks, E2S2 dominantly improves the performance of its powerful backbone models, e.g. BART and T5. For example, upon BART backbone, we achieve +1.1% averaged gain on the general language understanding evaluation (GLUE) benchmark and +1.75% F_0.5 score improvement on CoNLL2014 dataset. We also provide in-depth analyses to show the improvement stems from better linguistic representation. We hope that our work will foster future self-supervision research on seq2seq language model pretraining.

As an important fine-grained sentiment analysis problem, aspect-based sentiment analysis (ABSA), aiming to analyze and understand people's opinions at the aspect level, has been attracting considerable interest in the last decade. To handle ABSA in different scenarios, various tasks are introduced for analyzing different sentiment elements and their relations, including the aspect term, aspect category, opinion term, and sentiment polarity. Unlike early ABSA works focusing on a single sentiment element, many compound ABSA tasks involving multiple elements have been studied in recent years for capturing more complete aspect-level sentiment information. However, a systematic review of various ABSA tasks and their corresponding solutions is still lacking, which we aim to fill in this survey. More specifically, we provide a new taxonomy for ABSA which organizes existing studies from the axes of concerned sentiment elements, with an emphasis on recent advances of compound ABSA tasks. From the perspective of solutions, we summarize the utilization of pre-trained language models for ABSA, which improved the performance of ABSA to a new stage. Besides, techniques for building more practical ABSA systems in cross-domain/lingual scenarios are discussed. Finally, we review some emerging topics and discuss some open challenges to outlook potential future directions of ABSA.

大型预训练的语言模型（PLM）的最新进展导致了自然语言理解（NLU）任务的令人印象深刻的增长，并具有特定于任务的微调。但是，直接调整PLM在很大程度上依赖大量的标记实例，这些实例通常很难获得。迅速对PLM的调整已被证明对各种少数次任务很有价值。现有的作品研究基于迅速的NLU任务的基于及时的调整，主要集中于用语言器来得出正确的标签单词或生成及时的模板，以从PLM中启发语义。此外，还对常规数据增强方法进行了验证，可用于少量射击任务。但是，目前几乎没有针对基于及时的调整范式设计的数据增强方法。因此，我们研究了迅速的少数射击学习者的新数据增强问题。由于标签语义对于迅速的调整至关重要，因此我们提出了一种新颖的标签引导数据增强方法促进DA，该方法利用了丰富的标签语义信息以进行数据增强。很少的文本分类任务的广泛实验结果表明，我们提出的框架通过有效利用标签语义和数据扩展来实现自然语言理解来实现卓越的性能。

作为有效的策略，数据增强（DA）减轻了深度学习技术可能失败的数据稀缺方案。它广泛应用于计算机视觉，然后引入自然语言处理并实现了许多任务的改进。DA方法的主要重点之一是提高培训数据的多样性，从而帮助模型更好地推广到看不见的测试数据。在本调查中，我们根据增强数据的多样性，将DA方法框架为三类，包括释义，注释和采样。我们的论文根据上述类别，详细分析了DA方法。此外，我们还在NLP任务中介绍了他们的应用以及挑战。

在以前的作品中广泛讨论了句子语义相似性的原始伯特的表现不佳。我们发现不满意的性能主要是由于静态令牌嵌入偏差和无效的伯特层，而不是姓氏的高余弦相似性。为此，我们提出了一个迅速的句子嵌入方法，可以减少令牌嵌入偏差，使原始伯特层更有效。通过将句子嵌入式任务重新塑造为填充空白问题，我们的方法显着提高了原始伯特的性能。我们讨论了两个提示符，表示基于及时的句子嵌入的三个提示搜索方法。此外，我们提出了一种通过模板去噪技术的新型无监督培训目标，这大大缩短了监督和无人监督的环境之间的性能差距。对于实验，我们评估我们在非微调和微调的设置上的方法。即使是非微调方法也可以优于STS任务上的无监督服务器等微调的方法。我们的微调方法在无监督和监督设置中优于最先进的方法SIMCSE。与SIMCSE相比，我们分别在无监督环境下实现了2.29和2.58点的伯特和罗伯塔的改进。

立场检测旨在确定文本的作者是否赞成，反对或中立。这项任务的主要挑战是两个方面的：由于不同目标以及缺乏目标的上下文信息而产生的几乎没有学习。现有作品主要通过设计基于注意力的模型或引入嘈杂的外部知识来解决第二期，而第一个问题仍未探索。在本文中，受到预训练的语言模型（PLM）的潜在能力（PLM）的启发，我们建议介绍基于立场检测的及时基于迅速的微调。 PLM可以为目标提供基本的上下文信息，并通过提示启用几次学习。考虑到目标在立场检测任务中的关键作用，我们设计了目标感知的提示并提出了一种新颖的语言。我们的语言器不会将每个标签映射到具体单词，而是将每个标签映射到矢量，并选择最能捕获姿势与目标之间相关性的标签。此外，为了减轻通过单人工提示来处理不同目标的可能缺陷，我们建议将信息从多个提示中学到的信息提炼。实验结果表明，我们提出的模型在全数据和少数场景中的表现出色。

用于预培训语言模型的自我监督学习的核心包括预训练任务设计以及适当的数据增强。语言模型中的大多数数据增强都是独立于上下文的。最近在电子中提出了一个开创性的增强，并通过引入辅助生成网络（发电机）来实现最先进的性能，以产生用于培训主要辨别网络（鉴别者）的上下文化数据增强。然而，这种设计引入了发电机的额外计算成本，并且需要调整发电机和鉴别器之间的相对能力。在本文中，我们提出了一种自增强策略（SAS），其中单个网络用于审视以后的时期的培训常规预训练和上下文化数据增强。基本上，该策略消除了单独的发电机，并使用单个网络共同执行具有MLM（屏蔽语言建模）和RTD（替换令牌检测）头的两个预训练任务。它避免了寻找适当大小的发电机的挑战，这对于在电子中证明的性能至关重要，以及其随后的变体模型至关重要。此外，SAS是一项常规策略，可以与最近或将来的许多新技术无缝地结合，例如杜伯塔省的解除关注机制。我们的实验表明，SAS能够在具有相似或更少的计算成本中优于胶水任务中的电磁和其他最先进的模型。

Recent studies have revealed the intriguing few-shot learning ability of pretrained language models (PLMs): They can quickly adapt to a new task when fine-tuned on a small amount of labeled data formulated as prompts, without requiring abundant task-specific annotations. Despite their promising performance, most existing few-shot approaches that only learn from the small training set still underperform fully supervised training by nontrivial margins. In this work, we study few-shot learning with PLMs from a different perspective: We first tune an autoregressive PLM on the few-shot samples and then use it as a generator to synthesize a large amount of novel training samples which augment the original training set. To encourage the generator to produce label-discriminative samples, we train it via weighted maximum likelihood where the weight of each token is automatically adjusted based on a discriminative meta-learning objective. A classification PLM can then be fine-tuned on both the few-shot and the synthetic samples with regularization for better generalization and stability. Our approach FewGen achieves an overall better result across seven classification tasks of the GLUE benchmark than existing few-shot learning methods, improving no-augmentation methods by 5+ average points, and outperforming augmentation methods by 3+ average points.

Contrastive learning has become a new paradigm for unsupervised sentence embeddings. Previous studies focus on instance-wise contrastive learning, attempting to construct positive pairs with textual data augmentation. In this paper, we propose a novel Contrastive learning method with Prompt-derived Virtual semantic Prototypes (ConPVP). Specifically, with the help of prompts, we construct virtual semantic prototypes to each instance, and derive negative prototypes by using the negative form of the prompts. Using a prototypical contrastive loss, we enforce the anchor sentence embedding to be close to its corresponding semantic prototypes, and far apart from the negative prototypes as well as the prototypes of other sentences. Extensive experimental results on semantic textual similarity, transfer, and clustering tasks demonstrate the effectiveness of our proposed model compared to strong baselines. Code is available at https://github.com/lemon0830/promptCSE.

基于方面的情绪分析旨在确定产品评论中特定方面的情感极性。我们注意到，大约30％的评论不包含明显的观点词，但仍然可以传达清晰的人类感知情绪取向，称为隐含情绪。然而，最近的基于神经网络的方法几乎没有关注隐性情绪，这一审查有所关注。为了克服这个问题，我们通过域名语言资源检索的大规模情绪注释的Corpora采用监督对比培训。通过将隐式情感表达式的表示对准与具有相同情绪标签的人，预培训过程可以更好地捕获隐含和明确的情绪方向，以便在评论中的方面。实验结果表明，我们的方法在Semeval2014基准上实现了最先进的性能，综合分析验证了其对学习隐含情绪的有效性。

我们提出了Patron，这是一种新方法，它使用基于及时的不确定性估计，用于在冷启动场景下进行预训练的语言模型进行微调的数据选择，即，没有初始标记的数据可用。在顾客中，我们设计（1）一种基于迅速的不确定性传播方法来估计数据点的重要性和（2）分区 - 然后 - 剥离（PTR）策略，以促进对注释的样品多样性。六个文本分类数据集的实验表明，赞助人的表现优于最强的冷启动数据选择基准，高达6.9％。此外，仅具有128个标签，顾客分别基于香草微调和及时的学习，获得了91.0％和92.1％的全面监督性能。我们的赞助人实施可在\ url {https://github.com/yueyu1030/patron}上获得。

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.

Self-training (ST) has prospered again in language understanding by augmenting the fine-tuning of pre-trained language models when labeled data is insufficient. However, it remains challenging to incorporate ST into attribute-controllable language generation. Augmented by only self-generated pseudo text, generation models over-emphasize exploitation of the previously learned space, suffering from a constrained generalization boundary. We revisit ST and propose a novel method, DuNST to alleviate this problem. DuNST jointly models text generation and classification with a shared Variational AutoEncoder and corrupts the generated pseudo text by two kinds of flexible noise to disturb the space. In this way, our model could construct and utilize both pseudo text from given labels and pseudo labels from available unlabeled text, which are gradually refined during the ST process. We theoretically demonstrate that DuNST can be regarded as enhancing exploration towards the potential real text space, providing a guarantee of improved performance. Experiments on three controllable generation tasks show that DuNST could significantly boost control accuracy while maintaining comparable generation fluency and diversity against several strong baselines.

Recent studies have shown the impressive efficacy of counterfactually augmented data (CAD) for reducing NLU models' reliance on spurious features and improving their generalizability. However, current methods still heavily rely on human efforts or task-specific designs to generate counterfactuals, thereby impeding CAD's applicability to a broad range of NLU tasks. In this paper, we present AutoCAD, a fully automatic and task-agnostic CAD generation framework. AutoCAD first leverages a classifier to unsupervisedly identify rationales as spans to be intervened, which disentangles spurious and causal features. Then, AutoCAD performs controllable generation enhanced by unlikelihood training to produce diverse counterfactuals. Extensive evaluations on multiple out-of-domain and challenge benchmarks demonstrate that AutoCAD consistently and significantly boosts the out-of-distribution performance of powerful pre-trained models across different NLU tasks, which is comparable or even better than previous state-of-the-art human-in-the-loop or task-specific CAD methods. The code is publicly available at https://github.com/thu-coai/AutoCAD.

基于方面的情感分析（ABSA）旨在预测对给定方面表达的情感极性（SC）或提取意见跨度（OE）。 ABSA的先前工作主要依赖于相当复杂的特定方面特征诱导。最近，审计的语言模型（PLM），例如伯特（Bert）已被用作上下文建模层，以简化特征感应结构并实现最新性能。但是，这种基于PLM的上下文建模可能不是特定于方面的。因此，一个关键问题的探索还不足：如何通过PLM更好地建模特定方面的上下文？为了回答这个问题，我们试图以非侵入性的方式通过PLM增强特定方面的上下文建模。我们提出了三个特定于方面的输入转换，即伴侣，方面提示和方面标记。通过这些转变，可以实现非侵入性方面的PLM，以促进PLM，以便更多地关注句子中特定方面的环境。此外，我们为ABSA（ADVABSA）制定了对抗性基准，以查看特定于方面的建模如何影响模型的鲁棒性。 SC和OE的标准和对抗性基准的广泛实验结果证明了该方法的有效性和鲁棒性，从而在OE上产生了新的最新性能和SC上的竞争性能。

Natural Language Inference (NLI) or Recognizing Textual Entailment (RTE) aims at predicting the relation between a pair of sentences (premise and hypothesis) as entailment, contradiction or semantic independence. Although deep learning models have shown promising performance for NLI in recent years, they rely on large scale expensive human-annotated datasets. Semi-supervised learning (SSL) is a popular technique for reducing the reliance on human annotation by leveraging unlabeled data for training. However, despite its substantial success on single sentence classification tasks where the challenge in making use of unlabeled data is to assign "good enough" pseudo-labels, for NLI tasks, the nature of unlabeled data is more complex: one of the sentences in the pair (usually the hypothesis) along with the class label are missing from the data and require human annotations, which makes SSL for NLI more challenging. In this paper, we propose a novel way to incorporate unlabeled data in SSL for NLI where we use a conditional language model, BART to generate the hypotheses for the unlabeled sentences (used as premises). Our experiments show that our SSL framework successfully exploits unlabeled data and substantially improves the performance of four NLI datasets in low-resource settings. We release our code at: https://github.com/msadat3/SSL_for_NLI.

预训练模型已在许多代码智能任务中有效。这些模型在大规模未标记的语料库中进行了预训练，然后在下游任务中进行了微调。但是，由于预训练和下游任务的输入是不同的形式，因此很难充分探索预训练模型的知识。此外，微调的性能强烈依赖于下游数据的量，而实际上，具有稀缺数据的场景很常见。自然语言处理（NLP）领域的最新研究表明，迅速调整，一种调整的新范式，减轻上述问题并在各种NLP任务中实现了有希望的结果。在迅速调整中，在调整过程中插入的提示提供了特定于任务的知识，这对于具有相对较少数据的任务特别有益。在本文中，我们凭经验评估了代码智能任务中迅速调整的用法和效果。我们对流行的预训练模型Codebert和codet5进行及时调整，并尝试三个代码智能任务，包括缺陷预测，代码摘要和代码翻译。我们的实验结果表明，在所有三个任务中，迅速调整始终优于微调。此外，及时调整在低资源场景中显示出很大的潜力，例如，对于代码摘要，平均将微调的BLEU分数提高了26％以上。我们的结果表明，我们可以调整代码智能任务的迅速调整，以实现更好的性能，尤其是在缺乏特定于任务的数据时，我们可以调整及时调整。

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}.