Zhifei Li


2019

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Are You for Real? Detecting Identity Fraud via Dialogue Interactions
Weikang Wang | Jiajun Zhang | Qian Li | Chengqing Zong | Zhifei Li
Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP)

Identity fraud detection is of great importance in many real-world scenarios such as the financial industry. However, few studies addressed this problem before. In this paper, we focus on identity fraud detection in loan applications and propose to solve this problem with a novel interactive dialogue system which consists of two modules. One is the knowledge graph (KG) constructor organizing the personal information for each loan applicant. The other is structured dialogue management that can dynamically generate a series of questions based on the personal KG to ask the applicants and determine their identity states. We also present a heuristic user simulator based on problem analysis to evaluate our method. Experiments have shown that the trainable dialogue system can effectively detect fraudsters, and achieve higher recognition accuracy compared with rule-based systems. Furthermore, our learned dialogue strategies are interpretable and flexible, which can help promote real-world applications.

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Incremental Learning from Scratch for Task-Oriented Dialogue Systems
Weikang Wang | Jiajun Zhang | Qian Li | Mei-Yuh Hwang | Chengqing Zong | Zhifei Li
Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics

Clarifying user needs is essential for existing task-oriented dialogue systems. However, in real-world applications, developers can never guarantee that all possible user demands are taken into account in the design phase. Consequently, existing systems will break down when encountering unconsidered user needs. To address this problem, we propose a novel incremental learning framework to design task-oriented dialogue systems, or for short Incremental Dialogue System (IDS), without pre-defining the exhaustive list of user needs. Specifically, we introduce an uncertainty estimation module to evaluate the confidence of giving correct responses. If there is high confidence, IDS will provide responses to users. Otherwise, humans will be involved in the dialogue process, and IDS can learn from human intervention through an online learning module. To evaluate our method, we propose a new dataset which simulates unanticipated user needs in the deployment stage. Experiments show that IDS is robust to unconsidered user actions, and can update itself online by smartly selecting only the most effective training data, and hence attains better performance with less annotation cost.

2018

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A Teacher-Student Framework for Maintainable Dialog Manager
Weikang Wang | Jiajun Zhang | Han Zhang | Mei-Yuh Hwang | Chengqing Zong | Zhifei Li
Proceedings of the 2018 Conference on Empirical Methods in Natural Language Processing

Reinforcement learning (RL) is an attractive solution for task-oriented dialog systems. However, extending RL-based systems to handle new intents and slots requires a system redesign. The high maintenance cost makes it difficult to apply RL methods to practical systems on a large scale. To address this issue, we propose a practical teacher-student framework to extend RL-based dialog systems without retraining from scratch. Specifically, the “student” is an extended dialog manager based on a new ontology, and the “teacher” is existing resources used for guiding the learning process of the “student”. By specifying constraints held in the new dialog manager, we transfer knowledge of the “teacher” to the “student” without additional resources. Experiments show that the performance of the extended system is comparable to the system trained from scratch. More importantly, the proposed framework makes no assumption about the unsupported intents and slots, which makes it possible to improve RL-based systems incrementally.

2011

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Minimum Imputed-Risk: Unsupervised Discriminative Training for Machine Translation
Zhifei Li | Ziyuan Wang | Jason Eisner | Sanjeev Khudanpur | Brian Roark
Proceedings of the 2011 Conference on Empirical Methods in Natural Language Processing

2010

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Joshua 2.0: A Toolkit for Parsing-Based Machine Translation with Syntax, Semirings, Discriminative Training and Other Goodies
Zhifei Li | Chris Callison-Burch | Chris Dyer | Juri Ganitkevitch | Ann Irvine | Sanjeev Khudanpur | Lane Schwartz | Wren Thornton | Ziyuan Wang | Jonathan Weese | Omar Zaidan
Proceedings of the Joint Fifth Workshop on Statistical Machine Translation and MetricsMATR

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Unsupervised Discriminative Language Model Training for Machine Translation using Simulated Confusion Sets
Zhifei Li | Ziyuan Wang | Sanjeev Khudanpur | Jason Eisner
Coling 2010: Posters

2009

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Variational Decoding for Statistical Machine Translation
Zhifei Li | Jason Eisner | Sanjeev Khudanpur
Proceedings of the Joint Conference of the 47th Annual Meeting of the ACL and the 4th International Joint Conference on Natural Language Processing of the AFNLP

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Demonstration of Joshua: An Open Source Toolkit for Parsing-based Machine Translation
Zhifei Li | Chris Callison-Burch | Chris Dyer | Juri Ganitkevitch | Sanjeev Khudanpur | Lane Schwartz | Wren N. G. Thornton | Jonathan Weese | Omar F. Zaidan
Proceedings of the ACL-IJCNLP 2009 Software Demonstrations

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First- and Second-Order Expectation Semirings with Applications to Minimum-Risk Training on Translation Forests
Zhifei Li | Jason Eisner
Proceedings of the 2009 Conference on Empirical Methods in Natural Language Processing

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Efficient Extraction of Oracle-best Translations from Hypergraphs
Zhifei Li | Sanjeev Khudanpur
Proceedings of Human Language Technologies: The 2009 Annual Conference of the North American Chapter of the Association for Computational Linguistics, Companion Volume: Short Papers

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Joshua: An Open Source Toolkit for Parsing-Based Machine Translation
Zhifei Li | Chris Callison-Burch | Chris Dyer | Sanjeev Khudanpur | Lane Schwartz | Wren Thornton | Jonathan Weese | Omar Zaidan
Proceedings of the Fourth Workshop on Statistical Machine Translation

2008

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Optimal Dialog in Consumer-Rating Systems using POMDP Framework
Zhifei Li | Patrick Nguyen | Geoffrey Zweig
Proceedings of the 9th SIGdial Workshop on Discourse and Dialogue

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A Scalable Decoder for Parsing-Based Machine Translation with Equivalent Language Model State Maintenance
Zhifei Li | Sanjeev Khudanpur
Proceedings of the ACL-08: HLT Second Workshop on Syntax and Structure in Statistical Translation (SSST-2)

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Mining and Modeling Relations between Formal and Informal Chinese Phrases from Web Corpora
Zhifei Li | David Yarowsky
Proceedings of the 2008 Conference on Empirical Methods in Natural Language Processing

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Large-scale Discriminative n-gram Language Models for Statistical Machine Translation
Zhifei Li | Sanjeev Khudanpur
Proceedings of the 8th Conference of the Association for Machine Translation in the Americas: Research Papers

We extend discriminative n-gram language modeling techniques originally proposed for automatic speech recognition to a statistical machine translation task. In this context, we propose a novel data selection method that leads to good models using a fraction of the training data. We carry out systematic experiments on several benchmark tests for Chinese to English translation using a hierarchical phrase-based machine translation system, and show that a discriminative language model significantly improves upon a state-of-the-art baseline. The experiments also highlight the benefits of our data selection method.

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Unsupervised Translation Induction for Chinese Abbreviations using Monolingual Corpora
Zhifei Li | David Yarowsky
Proceedings of ACL-08: HLT