We develop novel first- and second-order features for dependency parsing based on the Google Syntactic Ngrams corpus, a collection of subtree counts of parsed sentences from scanned books. We also extend previous work on surface $n$-gram features from Web1T to the Google Books corpus and from first-order to second-order, comparing and analysing performance over newswire and web treebanks.
Surface and syntactic $n$-grams both produce substantial and complementary gains in parsing accuracy across domains. Our best system combines the two feature sets, achieving up to 0.8% absolute UAS improvements on newswire and 1.4% on web text.
Syntactic and semantic parsing has been investigated for decades, which is one primary topic in the natural language processing community. This article aims for a brief survey on this topic. The parsing community includes many tasks, which are difficult to be covered fully. Here we focus on two of the most popular formalizations of parsing: constituent parsing and dependency parsing. Constituent parsing is majorly targeted to syntactic analysis, and dependency parsing can handle both syntactic and semantic analysis. This article briefly reviews the representative models of constituent parsing …
Singapore University of Technology and Design（新加坡科技设计大学）
从NMT开始，编码器-解码器神经网络已被用于许多NLP问题。借用编码器组件的基于图形的模型和基于转换的模型分别在依存句法分析和成分语法分析上实现了最先进的性能。然而，还没有工作经验性地研究基于转换的解析的编码器-解码器神经网络。为此，我们应用了一个简单的编码器-解码器，在标准依赖性解析上实现了与Dyer et al.（2015）的解析器相当的结果，并在成分解析上优于Vinyals et al.（2015）的解析器。
University of Mannheim（曼海姆大学）；University of Cambridge（剑桥大学）
Traditional NLP has long held (supervised) syntactic parsing necessary for successful higher-level semantic language understanding (LU). The recent advent of end-to-end neural models, self-supervised via language modeling (LM), and their success on a wide range of LU tasks, however, questions this belief. In this work, we empirically investigate the usefulness of supervised parsing for semantic LU in the context of LM-pretrained transformer networks. Relying on the established fine-tuning paradigm, we first couple a pretrained transformer with a biaffine parsing head, aiming to infuse explicit…
Standard models for syntactic dependency parsing take words to be the elementary units that enter into dependency relations. In this paper, we investigate whether there are any benefits from enriching these models with the more abstract notion of nucleus proposed by Tesnière. We do this by showing how the concept of nucleus can be defined in the framework of Universal Dependencies and how we can use composition functions to make a transition-based dependency parser aware of this concept. Experiments on 12 languages show that nucleus composition gives small but significant improvements in parsi…
CAIT: A Syntactic Parsing Toolkit for Child-Adult InTeractions
Center for Language and Cognition (CLCG), University of Groningen（格罗宁根大学语言与认知中心）；Georgetown University（乔治城大学）；Computational Linguistics, Department of Linguistics, Bielefeld University（比勒菲尔德大学语言学系计算语言学）
Johns Hopkins University（约翰霍普金斯大学）；Microsoft Research（微软研究院）；University of Rochester（罗切斯特大学）
While numerous attempts have been made to jointly parse syntax and semantics, high performance in one domain typically comes at the price of performance in the other. This trade-off contradicts the large body of research focusing on the rich interactions at the syntax-semantics interface. We explore multiple model architectures which allow us to exploit the rich syntactic and semantic annotations contained in the Universal Decompositional Semantics (UDS) dataset, jointly parsing Universal Dependencies and UDS to obtain state-of-the-art results in both formalisms. We analyze the behaviour of a …
We reduce the task of (span-based) PropBank-style semantic role labeling (SRL) to syntactic dependency parsing. Our approach is motivated by our empirical analysis that shows three common syntactic patterns account for over 98% of the SRL annotations for both English and Chinese data. Based on this observation, we present a conversion scheme that packs SRL annotations into dependency tree representations through joint labels that permit highly accurate recovery back to the original format. This representation allows us to train statistical dependency parsers to tackle SRL and achieve competiti…
Syntactic parsing is the task of assigning a syntactic structure to a sentence. There are two popular syntactic parsing methods: constituency and dependency parsing. Recent works have used syntactic embeddings based on constituency trees, incremental top-down parsing, and other word syntactic features for brain activity prediction given the text stimuli to study how the syntax structure is represented in the brain's language network. However, the effectiveness of dependency parse trees or the relative predictive power of the various syntax parsers across brain areas, especially for the listeni…
University of Washington（华盛顿大学）；The Hong Kong University of Science and Technology（香港科技大学）；The Chinese University of Hong Kong (Shenzhen)（香港中文大学（深圳））；Shenzhen Research Institute of Big Data（深圳大数据研究院）
Constituency parsing is a fundamental and important task for natural language understanding, where a good representation of contextual information can help this task. N-grams, which is a conventional type of feature for contextual information, have been demonstrated to be useful in many tasks, and thus could also be beneficial for constituency parsing if they are appropriately modeled. In this paper, we propose span attention for neural chart-based constituency parsing to leverage n-gram information. Considering that current chart-based parsers with Transformer-based encoder represent spans by…
Enhancing Korean Dependency Parsing with Morphosyntactic Features
The University of British Columbia（不列颠哥伦比亚大学）；The Chinese University of Hong Kong（香港中文大学）；Seoul National University（首尔大学）；KAIST（韩国科学技术院）；Anyang University（安阳大学）
Parsing Through Boundaries in Chinese Word Segmentation
The Chinese University of Hong Kong, Hong Kong（香港中文大学）；University College London, United Kingdom（伦敦大学学院）；The University of British Columbia, Canada（不列颠哥伦比亚大学）
Most recent studies on neural constituency parsing focus on encoder structures, while few developments are devoted to decoders. Previous research has demonstrated that probabilistic statistical methods based on syntactic rules are particularly effective in constituency parsing, whereas syntactic rules are not used during the training of neural models in prior work probably due to their enormous computation requirements. In this paper, we first implement a fast CKY decoding procedure harnessing GPU acceleration, based on which we further derive a syntactic rule-based (rule-constrained) CKY deco…
Department of Computer Science and Engineering, Shanghai Jiao Tong University（上海交通大学计算机科学与工程系）；Key Laboratory of Shanghai Education Commission for Intelligent Interactionand Cognitive Engineering, Shanghai Jiao Tong University（上海市教育委员会智能交互与认知工程重点实验室（上海交通大学））；MoE Key Lab of Artificial Intelligence, AI Institute, Shanghai Jiao Tong University（教育部人工智能重点实验室（上海交通大学人工智能研究院））
Both syntactic and semantic structures are key linguistic contextual clues, in which parsing the latter has been well shown beneficial from parsing the former. However, few works ever made an attempt to let semantic parsing help syntactic parsing. As linguistic representation formalisms, both syntax and semantics may be represented in either span (constituent/phrase) or dependency, on both of which joint learning was also seldom explored. In this paper, we propose a novel joint model of syntactic and semantic parsing on both span and dependency representations, which incorporates syntactic inf…
Multi-Task Learning by using Contextualized Word Representations for Syntactic Parsing of a Morphologically Rich Language
VTT Technical Research Centre of Finland Ltd.（芬兰VTT技术研究中心有限公司）；University of Konstanz（康斯坦茨大学）；Al-Khawarizmi Institute of Computer Science（花剌子密计算机科学研究所）；University of Engineering and Technology（工程技术大学）；Umm Al-Qura University（乌姆·库拉大学）；Copenhagen University（哥本哈根大学）
We study the problem of integrating syntactic information from constituency trees into a neural model in Frame-semantic parsing sub-tasks, namely Target Identification (TI), FrameIdentification (FI), and Semantic Role Labeling (SRL). We use a Graph Convolutional Network to learn specific representations of constituents, such that each constituent is profiled as the production grammar rule it corresponds to. We leverage these representations to build syntactic features for each word in a sentence, computed as the sum of all the constituents on the path between a word and a task-specific node in…
University of Stuttgart（斯图加特大学）；Bosch Center for Artificial Intelligence（博世人工智能中心）
Modern graph-based syntactic dependency parsers operate by predicting, for each token within a sentence, a probability distribution over its possible syntactic heads (i.e., all other tokens) and then extracting a maximum spanning tree from the resulting log-probabilities. Nowadays, virtually all such parsers utilize deep neural networks and may thus be susceptible to miscalibration (in particular, overconfident predictions). In this paper, we prove that temperature scaling, a popular technique for post-hoc calibration of neural networks, cannot change the output of the aforementioned procedure…
IIT Bombay（印度理工学院孟买分校）；The University of Texas at Dallas（德克萨斯大学达拉斯分校）
Recently, unsupervised parsing of syntactic trees has gained considerable attention. A prototypical approach to such unsupervised parsing employs reinforcement learning and auto-encoders. However, no mechanism ensures that the learnt model leverages the well-understood language grammar. We propose an approach that utilizes very generic linguistic knowledge of the language present in the form of syntactic rules, thus inducing better syntactic structures. We introduce a novel formulation that takes advantage of the syntactic grammar rules and is independent of the base system. We achieve new sta…
New Zealand Institute for Language, Brain and Behaviour（新西兰语言、大脑与行为研究所）；University of Canterbury（坎特伯雷大学）；Geospatial Research Institute Toi Hangarau（Toi Hangarau地理空间研究所）
This paper analyses the degree to which dialect classifiers based on syntactic representations remain stable over space and time. While previous work has shown that the combination of grammar induction and geospatial text classification produces robust dialect models, we do not know what influence both changing grammars and changing populations have on dialect models. This paper constructs a test set for 12 dialects of English that spans three years at monthly intervals with a fixed spatial distribution across 1,120 cities. Syntactic representations are formulated within the usage-based Constr…
Content Differences in Syntactic and Semantic Representations
The Edmond and Lily Safra Center for Brain Sciences（埃德蒙与莉莉·萨夫拉脑科学中心）；School of Computer Science and Engineering（计算机科学与工程学院）；Hebrew University of Jerusalem（希伯来大学）
An Imitation Learning Approach to Unsupervised Parsing
Institute for Language, Cognition and Computation（语言、认知与计算研究所）；School of Informatics, University of Edinburgh（爱丁堡大学信息学院）；University of Waterloo（滑铁卢大学）
最近，人们对无监督解析器越来越感兴趣，这些解析器通常使用强化学习来优化面向语义的目标。不幸的是，学习的树通常与实际的语法树不匹配。Shen et al.（2018）提出了一种用于语言建模的结构化注意力机制（PRPN），它可以诱导更好的语法结构，但依赖于特定的语法。此外，他们的模型缺乏可解释性，因为它不是基于解析操作。在我们的工作中，我们提出了一种用于无监督解析的模仿学习方法，其中我们将PRPN诱导的句法知识转移到具有离散解析动作的Tree-LSTM模型。然后通过Gumbel-Softmax训练将其策略细化为面向语义的目标。我们在全自然语言推理数据集上评估了我们的方法，并表明它在解析$F$分数方面达到了新的技术水平，优于我们的基础模型，包括PRPN。
Salesforce Research（赛富时研究院）；Yale University（耶鲁大学）；University of Edinburgh（爱丁堡大学）；Facebook AI（脸书人工智能研究院）
We present GraPPa, an effective pre-training approach for table semantic parsing that learns a compositional inductive bias in the joint representations of textual and tabular data. We construct synthetic question-SQL pairs over high-quality tables via a synchronous context-free grammar (SCFG) induced from existing text-to-SQL datasets. We pre-train our model on the synthetic data using a novel text-schema linking objective that predicts the syntactic role of a table field in the SQL for each question-SQL pair. To maintain the model's ability to represent real-world data, we also include maske…
Nanyang Technological University（南洋理工大学）；Salesforce Research Asia（Salesforce亚洲研究院）；Institute for Infocomm Research, A-STAR（A*STAR资讯通信研究院）
We introduce a generic seq2seq parsing framework that casts constituency parsing problems (syntactic and discourse parsing) into a series of conditional splitting decisions. Our parsing model estimates the conditional probability distribution of possible splitting points in a given text span and supports efficient top-down decoding, which is linear in number of nodes. The conditional splitting formulation together with efficient beam search inference facilitate structural consistency without relying on expensive structured inference. Crucially, for discourse analysis we show that in our formul…
Google Research（谷歌研究院）；Bloomberg（彭博）；Cornell University（康奈尔大学）
English news headlines form a register with unique syntactic properties that have been documented in linguistics literature since the 1930s. However, headlines have received surprisingly little attention from the NLP syntactic parsing community. We aim to bridge this gap by providing the first news headline corpus of Universal Dependencies annotated syntactic dependency trees, which enables us to evaluate existing state-of-the-art dependency parsers on news headlines. To improve English news headline parsing accuracies, we develop a projection method to bootstrap silver training data from unla…
Domain-general semantic parsing is a long-standing goal in natural language processing, where the semantic parser is capable of robustly parsing sentences from domains outside of which it was trained. Current approaches largely rely on additional supervision from new domains in order to generalize to those domains. We present a generative model of natural language utterances and logical forms and demonstrate its application to semantic parsing. Our approach relies on domain-independent supervision to generalize to new domains. We derive and implement efficient algorithms for training, parsing,…
