Yan Xu


2021

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CAiRE in DialDoc21: Data Augmentation for Information Seeking Dialogue System
Yan Xu | Etsuko Ishii | Genta Indra Winata | Zhaojiang Lin | Andrea Madotto | Zihan Liu | Peng Xu | Pascale Fung
Proceedings of the 1st Workshop on Document-grounded Dialogue and Conversational Question Answering (DialDoc 2021)

Information-seeking dialogue systems, including knowledge identification and response generation, aim to respond to users with fluent, coherent, and informative responses based on users’ needs, which. To tackle this challenge, we utilize data augmentation methods and several training techniques with the pre-trained language models to learn a general pattern of the task and thus achieve promising performance. In DialDoc21 competition, our system achieved 74.95 F1 score and 60.74 Exact Match score in subtask 1, and 37.72 SacreBLEU score in subtask 2. Empirical analysis is provided to explain the effectiveness of our approaches.

2020

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CAiRE-COVID: A Question Answering and Query-focused Multi-Document Summarization System for COVID-19 Scholarly Information Management
Dan Su | Yan Xu | Tiezheng Yu | Farhad Bin Siddique | Elham Barezi | Pascale Fung
Proceedings of the 1st Workshop on NLP for COVID-19 (Part 2) at EMNLP 2020

We present CAiRE-COVID, a real-time question answering (QA) and multi-document summarization system, which won one of the 10 tasks in the Kaggle COVID-19 Open Research Dataset Challenge, judged by medical experts. Our system aims to tackle the recent challenge of mining the numerous scientific articles being published on COVID-19 by answering high priority questions from the community and summarizing salient question-related information. It combines information extraction with state-of-the-art QA and query-focused multi-document summarization techniques, selecting and highlighting evidence snippets from existing literature given a query. We also propose query-focused abstractive and extractive multi-document summarization methods, to provide more relevant information related to the question. We further conduct quantitative experiments that show consistent improvements on various metrics for each module. We have launched our website CAiRE-COVID for broader use by the medical community, and have open-sourced the code for our system, to bootstrap further study by other researches.

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Learning Knowledge Bases with Parameters for Task-Oriented Dialogue Systems
Andrea Madotto | Samuel Cahyawijaya | Genta Indra Winata | Yan Xu | Zihan Liu | Zhaojiang Lin | Pascale Fung
Findings of the Association for Computational Linguistics: EMNLP 2020

Task-oriented dialogue systems are either modularized with separate dialogue state tracking (DST) and management steps or end-to-end trainable. In either case, the knowledge base (KB) plays an essential role in fulfilling user requests. Modularized systems rely on DST to interact with the KB, which is expensive in terms of annotation and inference time. End-to-end systems, instead, use the KB directly as input, but they cannot scale when the KB is larger than a few hundred entries. In this paper, we propose a method to embed the KB, of any size, directly into the model parameters. The resulting model does not require any DST or template responses, nor the KB as input, and it can dynamically update its KB via fine-tuning. We evaluate our solution in five task-oriented dialogue datasets with small, medium, and large KB size. Our experiments show that end-to-end models can effectively embed knowledge bases in their parameters and achieve competitive performance in all evaluated datasets.

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Multi-hop Question Generation with Graph Convolutional Network
Dan Su | Yan Xu | Wenliang Dai | Ziwei Ji | Tiezheng Yu | Pascale Fung
Findings of the Association for Computational Linguistics: EMNLP 2020

Multi-hop Question Generation (QG) aims to generate answer-related questions by aggregating and reasoning over multiple scattered evidence from different paragraphs. It is a more challenging yet under-explored task compared to conventional single-hop QG, where the questions are generated from the sentence containing the answer or nearby sentences in the same paragraph without complex reasoning. To address the additional challenges in multi-hop QG, we propose Multi-Hop Encoding Fusion Network for Question Generation (MulQG), which does context encoding in multiple hops with Graph Convolutional Network and encoding fusion via an Encoder Reasoning Gate. To the best of our knowledge, we are the first to tackle the challenge of multi-hop reasoning over paragraphs without any sentence-level information. Empirical results on HotpotQA dataset demonstrate the effectiveness of our method, in comparison with baselines on automatic evaluation metrics. Moreover, from the human evaluation, our proposed model is able to generate fluent questions with high completeness and outperforms the strongest baseline by 20.8% in the multi-hop evaluation. on. The code is publicly availableat https://github.com/HLTCHKU

2019

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Incorporating Word and Subword Units in Unsupervised Machine Translation Using Language Model Rescoring
Zihan Liu | Yan Xu | Genta Indra Winata | Pascale Fung
Proceedings of the Fourth Conference on Machine Translation (Volume 2: Shared Task Papers, Day 1)

This paper describes CAiRE’s submission to the unsupervised machine translation track of the WMT’19 news shared task from German to Czech. We leverage a phrase-based statistical machine translation (PBSMT) model and a pre-trained language model to combine word-level neural machine translation (NMT) and subword-level NMT models without using any parallel data. We propose to solve the morphological richness problem of languages by training byte-pair encoding (BPE) embeddings for German and Czech separately, and they are aligned using MUSE (Conneau et al., 2018). To ensure the fluency and consistency of translations, a rescoring mechanism is proposed that reuses the pre-trained language model to select the translation candidates generated through beam search. Moreover, a series of pre-processing and post-processing approaches are applied to improve the quality of final translations.

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Learning to Learn Sales Prediction with Social Media Sentiment
Zhaojiang Lin | Andrea Madotto | Genta Indra Winata | Zihan Liu | Yan Xu | Cong Gao | Pascale Fung
Proceedings of the First Workshop on Financial Technology and Natural Language Processing

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CAiRE_HKUST at SemEval-2019 Task 3: Hierarchical Attention for Dialogue Emotion Classification
Genta Indra Winata | Andrea Madotto | Zhaojiang Lin | Jamin Shin | Yan Xu | Peng Xu | Pascale Fung
Proceedings of the 13th International Workshop on Semantic Evaluation

Detecting emotion from dialogue is a challenge that has not yet been extensively surveyed. One could consider the emotion of each dialogue turn to be independent, but in this paper, we introduce a hierarchical approach to classify emotion, hypothesizing that the current emotional state depends on previous latent emotions. We benchmark several feature-based classifiers using pre-trained word and emotion embeddings, state-of-the-art end-to-end neural network models, and Gaussian processes for automatic hyper-parameter search. In our experiments, hierarchical architectures consistently give significant improvements, and our best model achieves a 76.77% F1-score on the test set.

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Zero-shot Cross-lingual Dialogue Systems with Transferable Latent Variables
Zihan Liu | Jamin Shin | Yan Xu | Genta Indra Winata | Peng Xu | Andrea Madotto | Pascale Fung
Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP)

Despite the surging demands for multilingual task-oriented dialog systems (e.g., Alexa, Google Home), there has been less research done in multilingual or cross-lingual scenarios. Hence, we propose a zero-shot adaptation of task-oriented dialogue system to low-resource languages. To tackle this challenge, we first use a set of very few parallel word pairs to refine the aligned cross-lingual word-level representations. We then employ a latent variable model to cope with the variance of similar sentences across different languages, which is induced by imperfect cross-lingual alignments and inherent differences in languages. Finally, the experimental results show that even though we utilize much less external resources, our model achieves better adaptation performance for natural language understanding task (i.e., the intent detection and slot filling) compared to the current state-of-the-art model in the zero-shot scenario.

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Generalizing Question Answering System with Pre-trained Language Model Fine-tuning
Dan Su | Yan Xu | Genta Indra Winata | Peng Xu | Hyeondey Kim | Zihan Liu | Pascale Fung
Proceedings of the 2nd Workshop on Machine Reading for Question Answering

With a large number of datasets being released and new techniques being proposed, Question answering (QA) systems have witnessed great breakthroughs in reading comprehension (RC)tasks. However, most existing methods focus on improving in-domain performance, leaving open the research question of how these mod-els and techniques can generalize to out-of-domain and unseen RC tasks. To enhance the generalization ability, we propose a multi-task learning framework that learns the shared representation across different tasks. Our model is built on top of a large pre-trained language model, such as XLNet, and then fine-tuned on multiple RC datasets. Experimental results show the effectiveness of our methods, with an average Exact Match score of 56.59 and an average F1 score of 68.98, which significantly improves the BERT-Large baseline by8.39 and 7.22, respectively

2016

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Improved relation classification by deep recurrent neural networks with data augmentation
Yan Xu | Ran Jia | Lili Mou | Ge Li | Yunchuan Chen | Yangyang Lu | Zhi Jin
Proceedings of COLING 2016, the 26th International Conference on Computational Linguistics: Technical Papers

Nowadays, neural networks play an important role in the task of relation classification. By designing different neural architectures, researchers have improved the performance to a large extent in comparison with traditional methods. However, existing neural networks for relation classification are usually of shallow architectures (e.g., one-layer convolutional neural networks or recurrent networks). They may fail to explore the potential representation space in different abstraction levels. In this paper, we propose deep recurrent neural networks (DRNNs) for relation classification to tackle this challenge. Further, we propose a data augmentation method by leveraging the directionality of relations. We evaluated our DRNNs on the SemEval-2010 Task 8, and achieve an F1-score of 86.1%, outperforming previous state-of-the-art recorded results.

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How Transferable are Neural Networks in NLP Applications?
Lili Mou | Zhao Meng | Rui Yan | Ge Li | Yan Xu | Lu Zhang | Zhi Jin
Proceedings of the 2016 Conference on Empirical Methods in Natural Language Processing

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Compressing Neural Language Models by Sparse Word Representations
Yunchuan Chen | Lili Mou | Yan Xu | Ge Li | Zhi Jin
Proceedings of the 54th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)

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Natural Language Inference by Tree-Based Convolution and Heuristic Matching
Lili Mou | Rui Men | Ge Li | Yan Xu | Lu Zhang | Rui Yan | Zhi Jin
Proceedings of the 54th Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)

2015

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Classifying Relations via Long Short Term Memory Networks along Shortest Dependency Paths
Yan Xu | Lili Mou | Ge Li | Yunchuan Chen | Hao Peng | Zhi Jin
Proceedings of the 2015 Conference on Empirical Methods in Natural Language Processing

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Discriminative Neural Sentence Modeling by Tree-Based Convolution
Lili Mou | Hao Peng | Ge Li | Yan Xu | Lu Zhang | Zhi Jin
Proceedings of the 2015 Conference on Empirical Methods in Natural Language Processing