使用无法回答的问题的机器阅读理解是一项艰巨的NLP任务，受到无法从段落回答的问题的挑战。据观察，微妙的文字变化通常使一个可回答的问题无法回答，但是，大多数MRC模型无法识别此类变化。为了解决这个问题，在本文中，我们提出了一种基于跨度的对比度学习方法（SPANCL），该方法在答案跨度上明确将可回答的问题与他们的回答和无法回答的对应物进行了明确的对比。使用SPANCL，MRC模型被迫从微小的字面差异中感知至关重要的语义变化。小队2.0数据集的实验表明，SPANCL可以显着改善基准，从而产生0.86-2.14绝对EM的改进。其他实验还表明，Spancl是利用生成问题的有效方法。

由于低资源语言缺乏培训数据，交叉语言机器阅读理解（XMRC）是挑战。最近的方法仅使用培训数据，以资源丰富的语言，如英语到微调大规模的跨语法预训练的语言模型。由于语言之间的巨大差异，仅由源语言微调的模型可能无法对目标语言表现良好。有趣的是，我们观察到，虽然先前方法预测的前1个结果可能经常无法达到地面真理答案，但是正确的答案通常包含在Top-K预测结果中。基于这种观察，我们开发了一种两级方法来提高模型性能。召回的第一阶段目标：我们设计一个艰难的学习（HL）算法，以最大化顶级预测包含准确答案的可能性。第二阶段专注于精确：开发了答案感知对比学习（AA-CL）机制，以了解准确答案和其他候选者之间的细差异。我们的广泛实验表明，我们的模型在两个交叉语言MRC基准数据集上显着优于一系列强大的基线。

Existing pre-training methods for extractive Question Answering (QA) generate cloze-like queries different from natural questions in syntax structure, which could overfit pre-trained models to simple keyword matching. In order to address this problem, we propose a novel Momentum Contrastive pRe-training fOr queStion anSwering (MCROSS) method for extractive QA. Specifically, MCROSS introduces a momentum contrastive learning framework to align the answer probability between cloze-like and natural query-passage sample pairs. Hence, the pre-trained models can better transfer the knowledge learned in cloze-like samples to answering natural questions. Experimental results on three benchmarking QA datasets show that our method achieves noticeable improvement compared with all baselines in both supervised and zero-shot scenarios.

Human reading comprehension often requires reasoning of event semantic relations in narratives, represented by Event-centric Question-Answering (QA). To address event-centric QA, we propose a novel QA model with contrastive learning and invertible event transformation, call TranCLR. Our proposed model utilizes an invertible transformation matrix to project semantic vectors of events into a common event embedding space, trained with contrastive learning, and thus naturally inject event semantic knowledge into mainstream QA pipelines. The transformation matrix is fine-tuned with the annotated event relation types between events that occurred in questions and those in answers, using event-aware question vectors. Experimental results on the Event Semantic Relation Reasoning (ESTER) dataset show significant improvements in both generative and extractive settings compared to the existing strong baselines, achieving over 8.4% gain in the token-level F1 score and 3.0% gain in Exact Match (EM) score under the multi-answer setting. Qualitative analysis reveals the high quality of the generated answers by TranCLR, demonstrating the feasibility of injecting event knowledge into QA model learning. Our code and models can be found at https://github.com/LuJunru/TranCLR.

问题答案（QA）是自然语言处理中最具挑战性的最具挑战性的问题之一（NLP）。问答（QA）系统试图为给定问题产生答案。这些答案可以从非结构化或结构化文本生成。因此，QA被认为是可以用于评估文本了解系统的重要研究区域。大量的QA研究致力于英语语言，调查最先进的技术和实现最先进的结果。然而，由于阿拉伯QA中的研究努力和缺乏大型基准数据集，在阿拉伯语问答进展中的研究努力得到了很大速度的速度。最近许多预先接受的语言模型在许多阿拉伯语NLP问题中提供了高性能。在这项工作中，我们使用四个阅读理解数据集来评估阿拉伯QA的最先进的接种变压器模型，它是阿拉伯语 - 队，ArcD，AQAD和TYDIQA-GoldP数据集。我们微调并比较了Arabertv2基础模型，ArabertV0.2大型型号和ARAElectra模型的性能。在最后，我们提供了一个分析，了解和解释某些型号获得的低绩效结果。

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).

最近，在机器阅读理解（MRC）中广泛研究了注意力增强的多层编码器，例如变压器。为了预测答案，通常使用预测因子仅从最终编码层中汲取信息，该层生成源序列的粗粒表示，即段落和问题。分析表明，随着编码层的增加，源序列的表示会变得更粗糙。人们普遍认为，随着深度神经网络中越来越多的层数，编码过程将越来越多地为每个位置收集相关信息，从而导致更粗糙的表示形式，这增加了与其他位置相似的可能性（指均质性） 。这种现象会误导该模型做出错误的判断并降低表现。在本文中，我们认为，如果预测指标可以利用编码器不同粒度的表示形式，从而提供了源序列的不同视图，从而使模型的表达能力可以充分利用，那将是更好的。为此，我们提出了一种新型方法，称为自适应双向注意封闭网络（ABA-NET），该方法可自适应地利用不同级别的源代表向预测指标。此外，由于更好的表示是提高MRC性能的核心，因此胶囊网络和自我发项模块被仔细设计为我们编码器的构建块，该模块分别提供了探索本地和全球表示的能力。在三个基准数据集（即小队1.0，Squad 2.0和COQA）上进行的实验结果证明了我们方法的有效性。特别是，我们在小队1.0数据集上设置了新的最新性能

Supervised Question Answering systems (QA systems) rely on domain-specific human-labeled data for training. Unsupervised QA systems generate their own question-answer training pairs, typically using secondary knowledge sources to achieve this outcome. Our approach (called PIE-QG) uses Open Information Extraction (OpenIE) to generate synthetic training questions from paraphrased passages and uses the question-answer pairs as training data for a language model for a state-of-the-art QA system based on BERT. Triples in the form of <subject, predicate, object> are extracted from each passage, and questions are formed with subjects (or objects) and predicates while objects (or subjects) are considered as answers. Experimenting on five extractive QA datasets demonstrates that our technique achieves on-par performance with existing state-of-the-art QA systems with the benefit of being trained on an order of magnitude fewer documents and without any recourse to external reference data sources.

基于检索的对话响应选择旨在为给定多转中下文找到候选集的正确响应。基于预先训练的语言模型（PLMS）的方法对此任务产生了显着的改进。序列表示在对话背景和响应之间的匹配程度中扮演关键作用。然而，我们观察到相同上下文共享的不同的上下文响应对始终在由PLM计算的序列表示中具有更大的相似性，这使得难以区分来自负面的正响应。由此激励，我们提出了一种基于PLMS的响应选择任务的新颖\ TextBF {f} ine- \ textbf {g}下载\ textbf {g} unfrstive（fgc）学习方法。该FGC学习策略有助于PLMS在细粒中产生每个对话的更可区分的匹配表示，并进一步提高选择正反应的预测。两个基准数据集的实证研究表明，所提出的FGC学习方法一般可以提高现有PLM匹配模型的模型性能。

尽管现有的机器阅读理解模型在许多数据集上取得了迅速的进展，但它们远非强劲。在本文中，我们提出了一个面向理解的机器阅读理解模型，以解决三种鲁棒性问题，这些问题过于敏感，稳定性和泛化。具体而言，我们首先使用自然语言推理模块来帮助模型了解输入问题的准确语义含义，以解决过度敏感性和稳定性的问题。然后，在机器阅读理解模块中，我们提出了一种记忆引导的多头注意方法，该方法可以进一步很好地理解输入问题和段落的语义含义。第三，我们提出了一种多语言学习机制来解决概括问题。最后，这些模块与基于多任务学习的方法集成在一起。我们在三个旨在衡量模型稳健性的基准数据集上评估了我们的模型，包括Dureader（健壮）和两个与小队相关的数据集。广泛的实验表明，我们的模型可以很好地解决上述三种鲁棒性问题。而且，即使在某些极端和不公平的评估下，它也比所有这些数据集中所有这些数据集的最先进模型的结果要好得多。我们工作的源代码可在以下网址获得：https：//github.com/neukg/robustmrc。

预审前的语言模型通过提供高质量的上下文化单词嵌入来显着改善了下游语言理解任务（包括提取性问题）的性能。但是，培训问答模型仍然需要大量特定域的注释数据。在这项工作中，我们提出了一个合作的自我训练框架RGX，用于自动生成更非平凡的问题 - 解答对以提高模型性能。 RGX建立在带有答案实体识别器，问题生成器和答案提取器的交互式学习环境的蒙版答案提取任务上。给定带有蒙版实体的段落，生成器会在实体周围生成一个问题，并培训了提取器，以提取蒙面实体，并使用生成的问题和原始文本。该框架允许对任何文本语料库的问题产生和回答模型进行培训，而无需注释。实验结果表明，RGX优于最先进的语言模型（SOTA）的语言模型，并在标准提问基准的基准上采用转移学习方法，并在给定的模型大小和传输学习设置下产生新的SOTA性能。

对于开放式域问题的密集检索已被证明通过在问题通道对的大型数据集上培训来实现令人印象深刻的性能。我们调查是否可以以自我监督的方式学习密集的检索，并有效地应用没有任何注释。我们观察到这种情况下的检索斗争的现有借用模型，并提出了一种设计用于检索的新预制方案：重复跨度检索。我们在文档中使用经常性跨度来创建用于对比学习的伪示例。由此产生的模型 - 蜘蛛 - 在广泛的ODQA数据集上没有任何示例，并且与BM25具有竞争力，具有强烈的稀疏基线。此外，蜘蛛通常优于DPR在其他数据集的问题上培训的DPR培训的强大基线。我们将蜘蛛与BM25结合的混合猎犬改进了所有数据集的组件，并且通常与域中DPR模型具有竞争力，这些模型培训数万例培训。

预训练的语言模型（PLM）在自然语言理解中的许多下游任务中取得了显着的性能增长。已提出了各种中文PLM，以学习更好的中文表示。但是，大多数当前模型都使用中文字符作为输入，并且无法编码中文单词中包含的语义信息。虽然最近的预训练模型同时融合了单词和字符，但它们通常会遭受不足的语义互动，并且无法捕获单词和字符之间的语义关系。为了解决上述问题，我们提出了一个简单而有效的PLM小扣手，该小扣子采用了对单词和性格表示的对比度学习。特别是，Clower通过对多透明信息的对比学习将粗粒的信息（即单词）隐式编码为细粒度表示（即字符）。在现实的情况下，小电动器具有很大的价值，因为它可以轻松地将其纳入任何现有的基于细粒的PLM中而无需修改生产管道。在一系列下游任务上进行的扩展实验表明，小动物的卓越性能超过了几个最先进的实验 - 艺术基线。

Open-domain question answering relies on efficient passage retrieval to select candidate contexts, where traditional sparse vector space models, such as TF-IDF or BM25, are the de facto method. In this work, we show that retrieval can be practically implemented using dense representations alone, where embeddings are learned from a small number of questions and passages by a simple dualencoder framework. When evaluated on a wide range of open-domain QA datasets, our dense retriever outperforms a strong Lucene-BM25 system greatly by 9%-19% absolute in terms of top-20 passage retrieval accuracy, and helps our end-to-end QA system establish new state-of-the-art on multiple open-domain QA benchmarks. 1 * Equal contribution 1 The code and trained models have been released at https://github.com/facebookresearch/DPR.

We present SpanBERT, a pre-training method that is designed to better represent and predict spans of text. Our approach extends BERT by (1) masking contiguous random spans, rather than random tokens, and (2) training the span boundary representations to predict the entire content of the masked span, without relying on the individual token representations within it. Span-BERT consistently outperforms BERT and our better-tuned baselines, with substantial gains on span selection tasks such as question answering and coreference resolution. In particular, with the same training data and model size as BERT large , our single model obtains 94.6% and 88.7% F1 on SQuAD 1.1 and 2.0 respectively. We also achieve a new state of the art on the OntoNotes coreference resolution task (79.6% F1), strong performance on the TACRED relation extraction benchmark, and even gains on GLUE. 1 * Equal contribution. 1 Our code and pre-trained models are available at https://github.com/facebookresearch/ SpanBERT.

我们提供了从文本到文本变换器（T5）的第一次探索句子嵌入式。句子嵌入式广泛适用于语言处理任务。虽然T5在作为序列到序列映射问题的语言任务上实现令人印象深刻的性能，但目前尚不清楚如何从编码器解码器模型生成陈列嵌入的句子。我们调查三种方法提取T5句子嵌入方法：两个仅利用T5编码器，一个使用全T5编码器解码器模型。为了支持我们的调查，我们建立了一个新的句子代表转移基准，SentGlue，它将Senteval Toolkit扩展到粘合基准的九个任务。我们的编码器的型号优于Senteval和SentGlue传输任务的句子 - BERT和SIMCSE句子嵌入，包括语义文本相似性（STS）。发现从数百万到数十亿参数的缩放T5产生一致的进一步改进。最后，我们的编码器 - 解码器方法在使用句子嵌入时在STS上实现了新的最先进的。我们的模型在https://tfhub.dev/google/collections/sentence-t5/1发布。

This paper presents SimCSE, a simple contrastive learning framework that greatly advances state-of-the-art sentence embeddings. We first describe an unsupervised approach, which takes an input sentence and predicts itself in a contrastive objective, with only standard dropout used as noise. This simple method works surprisingly well, performing on par with previous supervised counterparts. We find that dropout acts as minimal data augmentation, and removing it leads to a representation collapse. Then, we propose a supervised approach, which incorporates annotated pairs from natural language inference datasets into our contrastive learning framework by using "entailment" pairs as positives and "contradiction" pairs as hard negatives. We evaluate SimCSE on standard semantic textual similarity (STS) tasks, and our unsupervised and supervised models using BERT base achieve an average of 76.3% and 81.6% Spearman's correlation respectively, a 4.2% and 2.2% improvement compared to the previous best results. We also show-both theoretically and empirically-that the contrastive learning objective regularizes pre-trained embeddings' anisotropic space to be more uniform, and it better aligns positive pairs when supervised signals are available. 1 2 We randomly sample 10 6 sentences from English Wikipedia and fine-tune BERTbase with learning rate = 3e-5, N = 64. In all our experiments, no STS training sets are used.

Label smoothing is a regularization technique widely used in supervised learning to improve the generalization of models on various tasks, such as image classification and machine translation. However, the effectiveness of label smoothing in multi-hop question answering (MHQA) has yet to be well studied. In this paper, we systematically analyze the role of label smoothing on various modules of MHQA and propose F1 smoothing, a novel label smoothing technique specifically designed for machine reading comprehension (MRC) tasks. We evaluate our method on the HotpotQA dataset and demonstrate its superiority over several strong baselines, including models that utilize complex attention mechanisms. Our results suggest that label smoothing can be effective in MHQA, but the choice of smoothing strategy can significantly affect performance.

Machine Reading Comprehension has become one of the most advanced and popular research topics in the fields of Natural Language Processing in recent years. The classification of answerability questions is a relatively significant sub-task in machine reading comprehension; however, there haven't been many studies. Retro-Reader is one of the studies that has solved this problem effectively. However, the encoders of most traditional machine reading comprehension models in general and Retro-Reader, in particular, have not been able to exploit the contextual semantic information of the context completely. Inspired by SemBERT, we use semantic role labels from the SRL task to add semantics to pre-trained language models such as mBERT, XLM-R, PhoBERT. This experiment was conducted to compare the influence of semantics on the classification of answerability for the Vietnamese machine reading comprehension. Additionally, we hope this experiment will enhance the encoder for the Retro-Reader model's Sketchy Reading Module. The improved Retro-Reader model's encoder with semantics was first applied to the Vietnamese Machine Reading Comprehension task and obtained positive results.

信息检索是自然语言处理中的重要组成部分，用于知识密集型任务，如问题应答和事实检查。最近，信息检索已经看到基于神经网络的密集检索器的出现，作为基于术语频率的典型稀疏方法的替代方案。这些模型在数据集和任务中获得了最先进的结果，其中提供了大型训练集。但是，它们不会很好地转移到没有培训数据的新域或应用程序，并且通常因未经监督的术语 - 频率方法（例如BM25）的术语频率方法而言。因此，自然问题是如果没有监督，是否有可能训练密集的索取。在这项工作中，我们探讨了对比学习的限制，作为培训无人监督的密集检索的一种方式，并表明它导致强烈的检索性能。更确切地说，我们在15个数据集中出现了我们的模型胜过BM25的Beir基准测试。此外，当有几千例的示例可用时，我们显示微调我们的模型，与BM25相比，这些模型导致强大的改进。最后，当在MS-Marco数据集上微调之前用作预训练时，我们的技术在Beir基准上获得最先进的结果。