A Novel Neural Network Model for Joint POS Tagging and Graph-based Dependency Parsing

We present a novel neural network model that learns POS tagging and graph-based dependency parsing jointly. Our model uses bidirectional LSTMs to learn feature representations shared for both POS tagging and dependency parsing tasks, thus handling the feature-engineering problem. Our extensive experiments, on 19 languages from the Universal Dependencies project, show that our model outperforms the state-of-the-art neural network-based Stack-propagation model for joint POS tagging and transition-based dependency parsing, resulting in a new state of the art. Our code is open-source and available together with pre-trained models at: https://github.com/datquocnguyen/jPTDPComment: v2: also include universal POS tagging, UAS and LAS accuracies w.r.t gold-standard segmentation on Universal Dependencies 2.0 - CoNLL 2017 shared task test data; in CoNLL 201

Reliability of Automatic Linguistic Annotation : Native vs Non-native Texts

Peer reviewe

An empirical study of maximum entropy approach for part-of-speech tagging of Vietnamese texts

International audienceThis paper presents an empirical study on the application of the maximum entropy approach for part-of-speech tagging of Vietnamese text, a language with special characteristics which largely distinguish it from occidental languages. Our best tagger explores and includes useful knowledge sources for tagging Vietnamese text and gives a 93.40%overall accuracy and a 80.69%unknown word accuracy on a test set of the Vietnamese treebank. Our tagger significantly outperforms the tagger that is being used for building the Vietnamese treebank, and as far as we are aware, this is the best tagging result ever published for the Vietnamese language.Nous présentons dans cet article une étude empirique de l'application de l'approche de l'entropie maximale pour l'étiquetage syntaxique de textes vietnamiens. Le vietnamien est une langue qui possède des caractéristiques spéciales qui la distinguent largement des langues occidentales. Notremeilleur étiqueteur explore et inclut des connaissances utiles qui, en terme de performance pour l'étiquetage de textes vietnamiens, fournit un taux de précision globale de 93.40% et de 80.69% pour les mots inconnus sur un ensemble de test du corpus arboré vietnamien. Notre étiqueteur est nettement supérieur à celui qui est en train d'être utilisé pour développer le corpus arboré vietnamien, et à l'heure actuelle c'est le meilleur résultat obtenu pour l'étiquetage de textes vietnamiens

An improved neural network model for joint POS tagging and dependency parsing

We propose a novel neural network model for joint part-of-speech (POS) tagging and dependency parsing. Our model extends the well-known BIST graph-based dependency parser (Kiperwasser and Goldberg, 2016) by incorporating a BiLSTM-based tagging component to produce automatically predicted POS tags for the parser. On the benchmark English Penn treebank, our model obtains strong UAS and LAS scores at 94.51% and 92.87%, respectively, producing 1.5+% absolute improvements to the BIST graph-based parser, and also obtaining a state-of-the-art POS tagging accuracy at 97.97%. Furthermore, experimental results on parsing 61 "big" Universal Dependencies treebanks from raw texts show that our model outperforms the baseline UDPipe (Straka and Strakov\'a, 2017) with 0.8% higher average POS tagging score and 3.6% higher average LAS score. In addition, with our model, we also obtain state-of-the-art downstream task scores for biomedical event extraction and opinion analysis applications. Our code is available together with all pre-trained models at: https://github.com/datquocnguyen/jPTDPComment: 11 pages; In Proceedings of the CoNLL 2018 Shared Task: Multilingual Parsing from Raw Text to Universal Dependencies, to appea

Empirical studies on word representations

One of the most fundamental tasks in natural language processing is representing words with mathematical objects (such as vectors). The word representations, which are most often estimated from data, allow capturing the meaning of words. They enable comparing words according to their semantic similarity, and have been shown to work extremely well when included in complex real-world applications. A large part of our work deals with ways of estimating word representations directly from large quantities of text. Our methods exploit the idea that words which occur in similar contexts have a similar meaning. How we define the context is an important focus of our thesis. The context can consist of a number of words to the left and to the right of the word in question, but, as we show, obtaining context words via syntactic links (such as the link between the verb and its subject) often works better. We furthermore investigate word representations that accurately capture multiple meanings of a single word. We show that translation of a word in context contains information that can be used to disambiguate the meaning of that word