统一的意见角色标签（ORL）旨在给予一篇文章检测一次拍摄中“意见持有人 - 目标”的所有可能的意见结构。不幸的是，现有的基于转换的统一方法受到更长的意见术语，并且无法解决术语重叠问题。通过采用基于跨度的图形模型实现了当前的最佳性能，然而仍然存在高模型复杂性并且在意见和角色之间的互动不足。在这项工作中，我们通过重新检测转换架构并使用指针网络（PINETNET）来调查新的解决方案。该框架在线性时间复杂度解析了所有意见结构，同时通过限制与PointNet的任何术语的限制。为了实现明确的观点 - 角色互动，我们进一步提出了一个统一的依赖性意见图（UDOG），共同建立了句法依赖结构和部分意见角色结构。然后，我们设计了居中性的图形聚合器（RCGA）以编码多关键udog，其中产生的高阶表示用于促进香草过渡系统中的预测。我们的模型在MPQA基准测试中实现了新的最先进结果。分析进一步证明了我们对疗效和效率的方法的优越性。

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.

Aspect Sentiment Triplet Extraction (ASTE) has become an emerging task in sentiment analysis research, aiming to extract triplets of the aspect term, its corresponding opinion term, and its associated sentiment polarity from a given sentence. Recently, many neural networks based models with different tagging schemes have been proposed, but almost all of them have their limitations: heavily relying on 1) prior assumption that each word is only associated with a single role (e.g., aspect term, or opinion term, etc. ) and 2) word-level interactions and treating each opinion/aspect as a set of independent words. Hence, they perform poorly on the complex ASTE task, such as a word associated with multiple roles or an aspect/opinion term with multiple words. Hence, we propose a novel approach, Span TAgging and Greedy infErence (STAGE), to extract sentiment triplets in span-level, where each span may consist of multiple words and play different roles simultaneously. To this end, this paper formulates the ASTE task as a multi-class span classification problem. Specifically, STAGE generates more accurate aspect sentiment triplet extractions via exploring span-level information and constraints, which consists of two components, namely, span tagging scheme and greedy inference strategy. The former tag all possible candidate spans based on a newly-defined tagging set. The latter retrieves the aspect/opinion term with the maximum length from the candidate sentiment snippet to output sentiment triplets. Furthermore, we propose a simple but effective model based on the STAGE, which outperforms the state-of-the-arts by a large margin on four widely-used datasets. Moreover, our STAGE can be easily generalized to other pair/triplet extraction tasks, which also demonstrates the superiority of the proposed scheme STAGE.

到目前为止，命名实体识别（ner）已经参与了三种主要类型，包括平面，重叠（嵌套）和不连续的ner，主要是单独研究。最近，为统一的人员建立了一个日益增长的兴趣，并与一个单一模型同时解决上述三个工作。当前最佳性能的方法主要包括基于跨度和序列到序列的模型，不幸的是，前者仅关注边界识别，后者可能遭受暴露偏差。在这项工作中，我们通过将统一的ner建模为Word-Word关系分类来提出一种小说替代方案，即W ^ 2ner。通过有效地建模具有下面邻近字（NNW）和尾页字 - *（THW- *）关系的实体单词之间的邻近关系来解决统一网内的内核瓶颈。基于W ^ 2ner方案，我们开发了一个神经框架，其中统一的网格被建模为单词对的2D网格。然后，我们提出了多粒度的2D卷积，以便更好地精炼网格表示。最后，共同预测器用于足够原因的单词关系。我们对14个广泛使用的基准数据集进行了广泛的实验，用于平板，重叠和不连续的NER（8英语和6个中文数据集），我们的型号击败了所有当前的顶级表演基线，推动了最先进的表演统一的网。

基于方面的情绪分析（ABSA）任务由三个典型的子特点组成：术语术语提取，意见术语提取和情感极性分类。这三个子组织通常是共同执行的，以节省资源并减少管道中的错误传播。但是，大多数现有联合模型只关注编码器共享的福利在子任务之间共享，但忽略差异。因此，我们提出了一个关节ABSA模型，它不仅享有编码器共享的好处，而且还专注于提高模型效率的差异。详细地，我们介绍了双编码器设计，其中一对编码器特别侧重于候选方识对分类，并且原始编码器对序列标记进行注意。经验结果表明，我们的拟议模型显示了鲁棒性，并显着优于前一个基准数据集的先前最先进。

方面情绪三重态提取（Aste）旨在识别目标，他们的情感极化和意见解释句子的情绪。 Aste可以自然地分为3个原子子组织，即目标检测，意见检测和情绪分类。我们认为针对目标 - 意见对的合适的子任务组合，组成特征提取，以及子任务之间的互动将是成功的关键。然而，由于缺陷的子任务制定，子最优特征表示或缺少子任务相互作用，在“一对多”或“多对一”的情况下可能导致不存在的情绪三体，或导出不存在的情绪三元组。在本文中，我们将Aste划分为目标 - 意见联合检测和情绪分类子任务，这与人类认知符合，并且相应地利用序列编码器和表编码器来处理它们。表编码器在令牌对等级提取情绪，从而可以容易地捕获目标和意见之间的组成特征。要在子任务之间建立显式交互，我们利用表格表示来指导序列编码，并将序列功能注入到表编码器中。实验表明，我们的模型在六个受欢迎的ASTE数据集中优于最先进的方法。

In order to achieve deep natural language understanding, syntactic constituent parsing is a vital step, highly demanded by many artificial intelligence systems to process both text and speech. One of the most recent proposals is the use of standard sequence-to-sequence models to perform constituent parsing as a machine translation task, instead of applying task-specific parsers. While they show a competitive performance, these text-to-parse transducers are still lagging behind classic techniques in terms of accuracy, coverage and speed. To close the gap, we here extend the framework of sequence-to-sequence models for constituent parsing, not only by providing a more powerful neural architecture for improving their performance, but also by enlarging their coverage to handle the most complex syntactic phenomena: discontinuous structures. To that end, we design several novel linearizations that can fully produce discontinuities and, for the first time, we test a sequence-to-sequence model on the main discontinuous benchmarks, obtaining competitive results on par with task-specific discontinuous constituent parsers and achieving state-of-the-art scores on the (discontinuous) English Penn Treebank.

Open Information Extraction (OpenIE) aims to extract relational tuples from open-domain sentences. Traditional rule-based or statistical models have been developed based on syntactic structures of sentences, identified by syntactic parsers. However, previous neural OpenIE models under-explore the useful syntactic information. In this paper, we model both constituency and dependency trees into word-level graphs, and enable neural OpenIE to learn from the syntactic structures. To better fuse heterogeneous information from both graphs, we adopt multi-view learning to capture multiple relationships from them. Finally, the finetuned constituency and dependency representations are aggregated with sentential semantic representations for tuple generation. Experiments show that both constituency and dependency information, and the multi-view learning are effective.

The rapid development of aspect-based sentiment analysis (ABSA) within recent decades shows great potential for real-world society. The current ABSA works, however, are mostly limited to the scenario of a single text piece, leaving the study in dialogue contexts unexplored. In this work, we introduce a novel task of conversational aspect-based sentiment quadruple analysis, namely DiaASQ, aiming to detect the sentiment quadruple of target-aspect-opinion-sentiment in a dialogue. DiaASQ bridges the gap between fine-grained sentiment analysis and conversational opinion mining. We manually construct a large-scale, high-quality Chinese dataset and also obtain the English version dataset via manual translation. We deliberately propose a neural model to benchmark the task. It advances in effectively performing end-to-end quadruple prediction and manages to incorporate rich dialogue-specific and discourse feature representations for better cross-utterance quadruple extraction. We finally point out several potential future works to facilitate the follow-up research of this new task. The DiaASQ data is open at https://github.com/unikcc/DiaASQ

We propose a transition-based approach that, by training a single model, can efficiently parse any input sentence with both constituent and dependency trees, supporting both continuous/projective and discontinuous/non-projective syntactic structures. To that end, we develop a Pointer Network architecture with two separate task-specific decoders and a common encoder, and follow a multitask learning strategy to jointly train them. The resulting quadratic system, not only becomes the first parser that can jointly produce both unrestricted constituent and dependency trees from a single model, but also proves that both syntactic formalisms can benefit from each other during training, achieving state-of-the-art accuracies in several widely-used benchmarks such as the continuous English and Chinese Penn Treebanks, as well as the discontinuous German NEGRA and TIGER datasets.

框架语义解析是一项基本的NLP任务，由三个子任务组成：框架标识，参数识别和角色分类。以前的大多数研究都倾向于忽略不同子任务与论点之间的关系，并且很少关注Framenet中定义的本体论框架知识。在本文中，我们提出了一个带有双层（KID）的知识引导的增量语义解析器。我们首先介绍框架知识图（FKG），这是一个构建框架知识上构建的框架和FES（帧元素）的异质图，以便我们可以得出框架和FES的知识增强表示。此外，我们提出了框架语义图（FSG）来表示用图形结构从文本中提取的框架语义结构。通过这种方式，我们可以将框架语义解析转变为增量图构造问题，以加强子任务之间的相互作用和参数之间的关系。我们的实验表明，在两个Framenet数据集上，KID的表现优于先前的最新方法1.7 f1得分。我们的代码可在https://github.com/pkunlp-icler/kid上使用。

语义角色标签（SRL）是NLP社区的一项基本而艰巨的任务。 SRL的最新作品主要分为两行：1）基于生物的； 2）基于跨度的。尽管普遍存在，但它们具有不考虑内部论证结构的一些内在缺点，可能会阻碍模型的表现力。关键挑战是参数是平坦的结构，并且在参数中没有确定的子树实现。为了解决这个问题，在本文中，我们建议将平坦的论点跨越为潜在子树，因此将SRL缩小为树解析任务。特别是，我们为制剂配备了新型的跨度限制的treecrf，以使树结构跨度感知，并将其进一步扩展到二阶情况。我们在Conll05和Conll12基准测试上进行了广泛的实验。结果表明，我们的方法的性能比所有以前的语法 - 不知不线作品都更好，在端到端和w/ w/ w/ gold prepticates设置下实现了新的最先进的作品。

事件提取（EE）是信息提取的重要任务，该任务旨在从非结构化文本中提取结构化事件信息。大多数先前的工作都专注于提取平坦的事件，同时忽略重叠或嵌套的事件。多个重叠和嵌套EE的模型包括几个连续的阶段来提取事件触发器和参数，这些阶段患有错误传播。因此，我们设计了一种简单而有效的标记方案和模型，以将EE作为单词关系识别，称为oneee。触发器或参数单词之间的关系在一个阶段同时识别出并行网格标记，从而产生非常快的事件提取速度。该模型配备了自适应事件融合模块，以生成事件感知表示表示和距离感知的预测指标，以整合单词关系识别的相对距离信息，从经验上证明这是有效的机制。对3个重叠和嵌套的EE基准测试的实验，即少数FC，GENIA11和GENIA13，表明Oneee实现了最新的（SOTA）结果。此外，ONEEE的推理速度比相同条件下的基线的推理速度快，并且由于它支持平行推断，因此可以进一步改善。

Prior works on Information Extraction (IE) typically predict different tasks and instances (e.g., event triggers, entities, roles, relations) independently, while neglecting their interactions and leading to model inefficiency. In this work, we introduce a joint IE framework, HighIE, that learns and predicts multiple IE tasks by integrating high-order cross-task and cross-instance dependencies. Specifically, we design two categories of high-order factors: homogeneous factors and heterogeneous factors. Then, these factors are utilized to jointly predict labels of all instances. To address the intractability problem of exact high-order inference, we incorporate a high-order neural decoder that is unfolded from a mean-field variational inference method. The experimental results show that our approach achieves consistent improvements on three IE tasks compared with our baseline and prior work.

方面情感三胞胎提取（ASTE）旨在提取方面，意见及其情感关系作为情感三胞胎的跨度。现有的作品通常将跨度检测作为1D令牌标记问题制定，并使用令牌对的2D标记矩阵对情感识别进行建模。此外，通过利用诸如伯特（Bert）之类的审计语言编码器（PLES）的代表形式，它们可以实现更好的性能。但是，他们只是利用将功能提取器作为提取器来构建其模块，但从未深入了解特定知识所包含的内容。在本文中，我们争辩说，与其进一步设计模块以捕获ASTE的电感偏见，不如包含“足够”的“足够”功能，用于1D和2D标记：（1）令牌表示包含令牌本身的上下文含义，因此此级别，因此此级别功能带有必要的信息以进行1D标记。 （2）不同PLE层的注意力矩阵可以进一步捕获令牌对中存在的多层次语言知识，从而使2D标记受益。 （3）此外，对于简单的转换，这两个功能也可以很容易地转换为2D标记矩阵和1D标记序列。这将进一步提高标签结果。通过这样做，PLE可以是自然的标记框架并实现新的最新状态，通过广泛的实验和深入分析来验证。

Lexicon信息和预先训练的型号，如伯特，已被组合以探索由于各自的优势而探索中文序列标签任务。然而，现有方法通过浅和随机初始化的序列层仅熔断词典特征，并且不会将它们集成到伯特的底层中。在本文中，我们提出了用于汉语序列标记的Lexicon增强型BERT（Lebert），其直接通过Lexicon适配器层将外部词典知识集成到BERT层中。与现有方法相比，我们的模型促进了伯特下层的深层词典知识融合。关于十个任务的十个中文数据集的实验，包括命名实体识别，单词分段和言语部分标记，表明Lebert实现了最先进的结果。

数据饥饿的深度神经网络已经将自己作为许多NLP任务的标准建立为包括传统序列标记的标准。尽管他们在高资源语言上表现最先进的表现，但它们仍然落后于低资源场景的统计计数器。一个方法来反击攻击此问题是文本增强，即，从现有数据生成新的合成训练数据点。虽然NLP最近目睹了一种文本增强技术的负载，但该领域仍然缺乏对多种语言和序列标记任务的系统性能分析。为了填补这一差距，我们调查了三类文本增强方法，其在语法（例如，裁剪子句子），令牌（例如，随机字插入）和字符（例如，字符交换）级别上执行更改。我们系统地将它们与语音标记，依赖解析和语义角色标记的分组进行了比较，用于使用各种模型的各种语言系列，包括依赖于诸如MBERT的普赖金的多语言语境化语言模型的架构。增强最显着改善了解析，然后是语音标记和语义角色标记的依赖性解析。我们发现实验技术通常在形态上丰富的语言，而不是越南语等分析语言。我们的研究结果表明，增强技术可以进一步改善基于MBERT的强基线。我们将字符级方法标识为最常见的表演者，而同义词替换和语法增强仪提供不一致的改进。最后，我们讨论了最大依赖于任务，语言对和模型类型的结果。

State-of-the-art named entity recognition systems rely heavily on hand-crafted features and domain-specific knowledge in order to learn effectively from the small, supervised training corpora that are available. In this paper, we introduce two new neural architectures-one based on bidirectional LSTMs and conditional random fields, and the other that constructs and labels segments using a transition-based approach inspired by shift-reduce parsers. Our models rely on two sources of information about words: character-based word representations learned from the supervised corpus and unsupervised word representations learned from unannotated corpora. Our models obtain state-of-the-art performance in NER in four languages without resorting to any language-specific knowledge or resources such as gazetteers. 1

我们通过纳入通用依赖性（UD）的句法特征来瞄准直接零射击设置中的跨语言机器阅读理解（MRC）的任务，以及我们使用的关键功能是每个句子中的语法关系。虽然以前的工作已经证明了有效的语法引导MRC模型，但我们建议采用句子际句法关系，除了基本的句子关系外，还可以进一步利用MRC任务的多句子输入中的句法依赖性。在我们的方法中，我们构建了句子间依赖图（ISDG）连接依赖树以形成横跨句子的全局句法关系。然后，我们提出了编码全局依赖关系图的ISDG编码器，通过明确地通过一个跳和多跳依赖性路径来解决句子间关系。三个多语言MRC数据集（XQUAD，MLQA，Tydiqa-Goldp）的实验表明，我们仅对英语培训的编码器能够在涵盖8种语言的所有14个测试集中提高零射性能，最高可达3.8 F1 / 5.2 EM平均改善，以及某些语言的5.2 F1 / 11.2 em。进一步的分析表明，改进可以归因于跨语言上一致的句法路径上的注意力。

Simile recognition involves two subtasks: simile sentence classification that discriminates whether a sentence contains simile, and simile component extraction that locates the corresponding objects (i.e., tenors and vehicles). Recent work ignores features other than surface strings. In this paper, we explore expressive features for this task to achieve more effective data utilization. Particularly, we study two types of features: 1) input-side features that include POS tags, dependency trees and word definitions, and 2) decoding features that capture the interdependence among various decoding decisions. We further construct a model named HGSR, which merges the input-side features as a heterogeneous graph and leverages decoding features via distillation. Experiments show that HGSR significantly outperforms the current state-of-the-art systems and carefully designed baselines, verifying the effectiveness of introduced features. Our code is available at https://github.com/DeepLearnXMU/HGSR.