At UCLA-NLP, our mission is to develop reliable, fair, accountable, robust natural language understanding and generation technology to benefit everyone.

Please see our recent papers at

In the following, we will highlight our research papers at EMNLP 2021 on the following topics:


Language Generation

[1], [2]
  1. AESOP: Paraphrase Generation with Adaptive Syntactic Control

    Jiao Sun, Xuezhe Ma, and Nanyun Peng, in EMNLP, 2021.
    QA Sessions: VIRTUAL POSTER SESSION II: GENERATION Paper link in the virtual conference
    BibTeX Details
    @inproceedings{sun2021aesop,
      title = {AESOP: Paraphrase Generation with Adaptive Syntactic Control},
      author = {Sun, Jiao and Ma, Xuezhe and Peng, Nanyun},
      booktitle = {EMNLP},
      presentation_id = {https://underline.io/events/192/posters/8242/poster/37911-aesop-paraphrase-generation-with-adaptive-syntactic-control},
      year = {2021}
    }
    

    Related Publications

    No related publications found.


    Details
  2. HypoGen: Hyperbole Generation with Commonsense and Counterfactual Knowledge

    Yufei Tian, Arvind krishna Sridhar, and Nanyun Peng, in EMNLP-Finding, 2021.
    QA Sessions: FINDINGS PAPERS - GENERATION Paper link in the virtual conference
    Full Text BibTeX Details
     A hyperbole is an intentional and creative exaggeration not to be taken literally. Despite its ubiquity in daily life, the computational explorations of hyperboles are scarce. In this paper, we tackle the under-explored and challenging task: sentence-level hyperbole generation. We start with a representative syntactic pattern for intensification and systematically study the semantic (commonsense and counterfactual) relationships between each component in such hyperboles. We then leverage commonsense and counterfactual inference to generate hyperbole candidates based on our findings from the pattern, and train neural classifiers to rank and select high-quality hyperboles. Automatic and human evaluations show that our generation method is able to generate hyperboles creatively with high success rate and intensity.
    @inproceedings{tian2021hypogen,
      title = {HypoGen: Hyperbole Generation with Commonsense and Counterfactual Knowledge},
      author = {Tian, Yufei and Sridhar, Arvind krishna and Peng, Nanyun},
      booktitle = {EMNLP-Finding},
      year = {2021},
      presentation_id = {https://underline.io/events/192/sessions/7923/lecture/38307-hypogen-hyperbole-generation-with-commonsense-and-counterfactual-knowledge}
    }
    

    Related Publications

    No related publications found.


    Details

Fairness and Robustness

[1], [2], [3]
  1. Harms of Gender Exclusivity and Challenges in Non-Binary Representation in Language Technologies

    Sunipa Dev, Masoud Monajatipoor, Anaelia Ovalle, Arjun Subramonian, Jeff Phillips, and Kai-Wei Chang, in EMNLP, 2021.
    QA Sessions: 4D: ETHICS AND NLP Paper link in the virtual conference
    Full Text Slides Poster BibTeX Details
    Gender is widely discussed in the context of language tasks and when examining the stereotypes propagated by language models. However, current discussions primarily treat gender as binary, which can perpetuate harms such as the cyclical erasure of non-binary gender identities. These harms are driven by model and dataset biases, which are consequences of the non-recognition and lack of understanding of non-binary genders in society. In this paper, we explain the complexity of gender and language around it, and survey non-binary persons to understand harms associated with the treatment of gender as binary in English language technologies. We also detail how current language representations (e.g., GloVe, BERT) capture and perpetuate these harms and related challenges that need to be acknowledged and addressed for representations to equitably encode gender information.
    @inproceedings{dev2021harms,
      title = {Harms of Gender Exclusivity and Challenges in Non-Binary Representation in Language Technologies},
      author = {Dev, Sunipa and Monajatipoor, Masoud and Ovalle, Anaelia and Subramonian, Arjun and Phillips, Jeff and Chang, Kai-Wei},
      presentation_id = {https://underline.io/events/192/sessions/7788/lecture/37320-harms-of-gender-exclusivity-and-challenges-in-non-binary-representation-in-language-technologies},
      blog_url = {https://uclanlp.medium.com/harms-of-gender-exclusivity-and-challenges-in-non-binary-representation-in-language-technologies-5f89891b5aee},
      booktitle = {EMNLP},
      year = {2021}
    }
    
    Details
  2. On the Transferability of Adversarial Attacks against Neural Text Classifier

    Liping Yuan, Xiaoqing Zheng, Yi Zhou, Cho-Jui Hsieh, and Kai-Wei Chang, in EMNLP, 2021.
    QA Sessions: VIRTUAL POSTER SESSION I: INTERPRETABILITY AND ANALYSIS OF MODELS FOR NLP Paper link in the virtual conference
    Full Text BibTeX Details
    Deep neural networks are vulnerable to adversarial attacks, where a small perturbation to an input alters the model prediction. In many cases, malicious inputs intentionally crafted for one model can fool another model. In this paper, we present the first study to systematically investigate the transferability of adversarial examples for text classification models and explore how various factors, including network architecture, tokenization scheme, word embedding, and model capacity, affect the transferability of adversarial examples. Based on these studies, we propose a genetic algorithm to find an ensemble of models that can be used to induce adversarial examples to fool almost all existing models. Such adversarial examples reflect the defects of the learning process and the data bias in the training set. Finally, we derive word replacement rules that can be used for model diagnostics from these adversarial examples.
    @inproceedings{yuan2021on,
      title = {On the Transferability of Adversarial Attacks against Neural Text Classifier},
      author = {Yuan, Liping and Zheng, Xiaoqing and Zhou, Yi and Hsieh, Cho-Jui and Chang, Kai-Wei},
      presentation_id = {https://underline.io/events/192/posters/8223/poster/38067-on-the-transferability-of-adversarial-attacks-against-neural-text-classifier},
      booktitle = {EMNLP},
      year = {2021}
    }
    

    Related Publications


    Details
  3. Searching for an Effiective Defender: Benchmarking Defense against Adversarial Word Substitution

    Zongyi Li, Jianhan Xu, Jiehang Zeng, Linyang Li, Xiaoqing Zheng, Qi Zhang, Kai-Wei Chang, and Cho-Jui Hsieh, in EMNLP, 2021.
    QA Sessions: VIRTUAL POSTER SESSION I: MACHINE LEARNING FOR NLP Paper link in the virtual conference
    Full Text BibTeX Details
    Recent studies have shown that deep neural networks are vulnerable to intentionally crafted adversarial examples, and various methods have been proposed to defend against adversarial word-substitution attacks for neural NLP models. However, there is a lack of systematic study on comparing different defense approaches under the same attacking setting. In this paper, we seek to fill the gap of systematic studies through comprehensive researches on understanding the behavior of neural text classifiers trained by various defense methods under representative adversarial attacks. In addition, we propose an effective method to further improve the robustness of neural text classifiers against such attacks and achieved the highest accuracy on both clean and adversarial examples on AGNEWS and IMDB datasets by a significant margin.
    @inproceedings{li2021searching,
      title = {Searching for an Effiective Defender: Benchmarking Defense against Adversarial Word Substitution},
      author = {Li, Zongyi and Xu, Jianhan and Zeng, Jiehang and Li, Linyang and Zheng, Xiaoqing and Zhang, Qi and Chang, Kai-Wei and Hsieh, Cho-Jui},
      presentation_id = {https://underline.io/events/192/posters/8225/poster/38025-searching-for-an-effective-defender-benchmarking-defense-against-adversarial-word-substitution},
      booktitle = {EMNLP},
      year = {2021}
    }
    
    Details

Multi-Modal, Multi-Lingual, and Culture Diversity

[1]
  1. Improving Pre-trained Vision-and-Language Embeddings for Phrase Grounding

    Zi-Yi Dou and Nanyun Peng, in EMNLP, 2021.
    QA Sessions: VIRTUAL POSTER SESSION II: SPEECH, VISION, ROBOTICS, MULTIMODAL GROUNDING Paper link in the virtual conference
    BibTeX Details
    @inproceedings{dou2021improving,
      title = {Improving Pre-trained Vision-and-Language Embeddings for Phrase Grounding},
      author = {Dou, Zi-Yi and Peng, Nanyun},
      booktitle = {EMNLP},
      presentation_id = {https://underline.io/events/192/posters/8255/poster/37595-improving-pre-trained-vision-and-language-embeddings-for-phrase-grounding},
      year = {2021}
    }
    

    Related Publications

    No related publications found.


    Details
[1], [2], [3]
  1. Improving Zero-Shot Cross-Lingual Transfer Learning via Robust Training

    Kuan-Hao Huang, Wasi Ahmad, Nanyun Peng, and Kai-Wei Chang, in EMNLP, 2021.
    QA Sessions: 3G - IN PERSON POSTER SESSION Paper link in the virtual conference
    Full Text Code BibTeX Details
    Pre-trained multilingual language encoders, such as multilingual BERT and XLM-R, show great potential for zero-shot cross-lingual transfer. However, these multilingual encoders do not precisely align words and phrases across languages. Especially, learning alignments in the multilingual embedding space usually requires sentence-level or word-level parallel corpora, which are expensive to be obtained for low-resource languages. An alternative is to make the multilingual encoders more robust; when fine-tuning the encoder using downstream task, we train the encoder to tolerate noise in the contextual embedding spaces such that even if the representations of different languages are not aligned well, the model can still achieve good performance on zero-shot cross-lingual transfer. In this work, we propose a learning strategy for training robust models by drawing connections between adversarial examples and the failure cases of zero-shot cross-lingual transfer. We adopt two widely used robust training methods, adversarial training and randomized smoothing, to train the desired robust model. The experimental results demonstrate that robust training improves zero-shot cross-lingual transfer on text classification tasks. The improvement is more significant in the generalized cross-lingual transfer setting, where the pair of input sentences belong to two different languages.
    @inproceedings{huang2021improving,
      title = {Improving Zero-Shot Cross-Lingual Transfer Learning via Robust Training},
      author = {Huang, Kuan-Hao and Ahmad, Wasi and Peng, Nanyun and Chang, Kai-Wei},
      presentation_id = {https://underline.io/events/192/posters/7783/poster/40656-improving-zero-shot-cross-lingual-transfer-learning-via-robust-training},
      booktitle = {EMNLP},
      year = {2021}
    }
    
    Details
  2. Broaden the Vision: Geo-Diverse Visual Commonsense Reasoning

    Da Yin, Liunian Harold Li, Ziniu Hu, Nanyun Peng, and Kai-Wei Chang, in EMNLP, 2021.
    QA Sessions: 4F: SPEECH, VISION, ROBOTICS, MULTIMODAL GROUNDING 1 Paper link in the virtual conference
    Full Text Code BibTeX Details
    Commonsense is defined as the knowledge that is shared by everyone. However, certain types of commonsense knowledge are correlated with culture and geographic locations and they are only shared locally. For example, the scenarios of wedding ceremonies vary across regions due to different customs influenced by historical and religious factors. Such regional characteristics, however, are generally omitted in prior work. In this paper, we construct a Geo-Diverse Visual Commonsense Reasoning dataset (GD-VCR) to test vision-and-language models’ ability to understand cultural and geo-location-specific commonsense. In particular, we study two state-of-the-art Vision-and-Language models, VisualBERT and ViLBERT trained on VCR, a standard multimodal commonsense benchmark with images primarily from Western regions. We then evaluate how well the trained models can generalize to answering the questions in GD-VCR. We find that the performance of both models for non-Western regions including East Asia, South Asia, and Africa is significantly lower than that for Western region. We analyze the reasons behind the performance disparity and find that the performance gap is larger on QA pairs that: 1) are concerned with culture-related scenarios, e.g., weddings, religious activities, and festivals; 2) require high-level geo-diverse commonsense reasoning rather than low-order perception and recognition.
    @inproceedings{yin2021broaden,
      title = {	Broaden the Vision: Geo-Diverse Visual Commonsense Reasoning},
      author = {Yin, Da and Li, Liunian Harold and Hu, Ziniu and Peng, Nanyun and Chang, Kai-Wei},
      booktitle = {EMNLP},
      presentation_id = {https://underline.io/events/192/sessions/7790/lecture/37514-broaden-the-vision-geo-diverse-visual-commonsense-reasoning},
      year = {2021}
    }
    
    Details
  3. Retrieval Augmented Code Generation and Summarization

    Md Rizwan Parvez, Wasi Ahmad, Saikat Chakraborty, Baishakhi Ray, and Kai-Wei Chang, in EMNLP-Finding, 2021.
    QA Sessions: FINDINGS PAPERS - GENERATION Paper link in the virtual conference
    Full Text BibTeX Details
    Software developers write a lot of source code and documentation during software development. Intrinsically, developers often recall parts of source code or code summaries that they had written in the past while implementing software or documenting them. To mimic developers’ code or summary generation behavior, we propose a retrieval augmented framework, \tool, that retrieves relevant code or summaries from a retrieval database and provides them as a supplement to code generation or summarization models. \tool has a couple of uniqueness. First, it extends the state-of-the-art dense retrieval technique to search for relevant code or summaries. Second, it can work with retrieval databases that include unimodal (only code or natural language description) or bimodal instances (code-description pairs). We conduct experiments and extensive analysis on two benchmark datasets of code generation and summarization in Java and Python, and the promising results endorse the effectiveness of our proposed retrieval augmented framework.
    @inproceedings{parvez2021retrieval,
      title = {Retrieval Augmented Code Generation and Summarization},
      author = {Parvez, Md Rizwan and Ahmad, Wasi and Chakraborty, Saikat and Ray, Baishakhi and Chang, Kai-Wei},
      booktitle = {EMNLP-Finding},
      presentation_id = {https://underline.io/events/192/sessions/7923/lecture/38314-retrieval-augmented-code-generation-and-summarization},
      year = {2021}
    }
    
    Details

Information Extraction and Question Answering

[1], [2], [3], [4]
  1. Document-level Entity-based Extraction as Template Generation

    Kung-Hsiang Huang, Sam Tang, and Nanyun Peng, in EMNLP, 2021.
    QA Sessions: VIRTUAL POSTER SESSION II: INFORMATION EXTRACTION Paper link in the virtual conference
    BibTeX Details
    @inproceedings{huang2021tempgen,
      title = {Document-level Entity-based Extraction as Template Generation},
      author = {Huang, Kung-Hsiang and Tang, Sam and Peng, Nanyun},
      booktitle = {EMNLP},
      presentation_id = {https://underline.io/events/192/posters/8243/poster/37467-document-level-entity-based-extraction-as-template-generation},
      year = {2021}
    }
    

    Related Publications

    No related publications found.


    Details
  2. ESTER: A Machine Reading Comprehension Dataset for Event Semantic Relation Reasoning

    Rujun Han, I.-Hung Hsu, Jiao Sun, Julia Baylon, Qiang Ning, Dan Roth, and Nanyun Peng, in EMNLP, 2021.
    QA Sessions: 7D: RESOURCES AND EVALUATION 3 Paper link in the virtual conference
    Full Text Code BibTeX Details
    @inproceedings{han2021ester,
      title = {ESTER: A Machine Reading Comprehension Dataset for Event Semantic Relation Reasoning},
      author = {Han, Rujun and Hsu, I-Hung and Sun, Jiao and Baylon, Julia and Ning, Qiang and Roth, Dan and Peng, Nanyun},
      booktitle = {EMNLP},
      presentation_id = {https://underline.io/events/192/sessions/7816/lecture/37869-ester-a-machine-reading-comprehension-dataset-for-reasoning-about-event-semantic-relations},
      year = {2021}
    }
    

    Related Publications

    1. ECONET: Effective Continual Pretraining of Language Models for Event Temporal Reasoning, EMNLP, 2021
    2. EventPlus: A Temporal Event Understanding Pipeline, 2021 Annual Conference of the North American Chapter of the Association for Computational Linguistics (NAACL), Demonstrations Track, 2021

    Details
  3. ECONET: Effective Continual Pretraining of Language Models for Event Temporal Reasoning

    Rujun Han, Xiang Ren, and Nanyun Peng, in EMNLP, 2021.
    QA Sessions: VIRTUAL POSTER SESSION II: INFORMATION EXTRACTION Paper link in the virtual conference
    Full Text Code BibTeX Details
    @inproceedings{han2021econet,
      title = {ECONET: Effective Continual Pretraining of Language Models for Event Temporal Reasoning},
      author = {Han, Rujun and Ren, Xiang and Peng, Nanyun},
      booktitle = {EMNLP},
      presentation_id = {https://underline.io/events/192/posters/8243/poster/37875-econet-effective-continual-pretraining-of-language-models-for-event-temporal-reasoning},
      year = {2021}
    }
    

    Related Publications

    1. ESTER: A Machine Reading Comprehension Dataset for Event Semantic Relation Reasoning, EMNLP, 2021
    2. EventPlus: A Temporal Event Understanding Pipeline, 2021 Annual Conference of the North American Chapter of the Association for Computational Linguistics (NAACL), Demonstrations Track, 2021

    Details
  4. HyperExpan: Taxonomy Expansion with Hyperbolic Representation Learning

    Mingyu Derek Ma, Muhao Chen, Te-Lin Wu, and Nanyun Peng, in EMNLP-Finding, 2021.
    QA Sessions: FINDINGS PAPERS - SEMANTICS: LEXICAL, SENTENCE LEVEL, TEXTUAL INFERENCE AND OTHER AREAS Paper link in the virtual conference
    Full Text Slides BibTeX Details
    Taxonomies are valuable resources for many applications, but the limited coverage due to the expensive manual curation process hinders their general applicability. Prior works attempt to automatically expand existing taxonomies to improve their coverage by learning concept embeddings in Euclidean space, while taxonomies, inherently hierarchical, more naturally align with the geometric properties of a hyperbolic space. In this paper, we present HyperExpan, a taxonomy expansion algorithm that seeks to preserve the structure of a taxonomy in a more expressive hyperbolic embedding space and learn to represent concepts and their relations with a Hyperbolic Graph Neural Network (HGNN). Specifically, HyperExpan leverages position embeddings to exploit the structure of the existing taxonomies, and characterizes the concept profile information to support the inference on unseen concepts during training. Experiments show that our proposed HyperExpan outperforms baseline models with representation learning in a Euclidean feature space and achieves state-of-the-art performance on the taxonomy expansion benchmarks.
    @inproceedings{ma2021hyperexpan,
      title = {HyperExpan: Taxonomy Expansion with Hyperbolic Representation Learning},
      author = {Ma, Mingyu Derek and Chen, Muhao and Wu, Te-Lin and Peng, Nanyun},
      booktitle = {EMNLP-Finding},
      year = {2021},
      presentation_id = {https://underline.io/events/192/sessions/7934/lecture/38572-hyperexpan-taxonomy-expansion-with-hyperbolic-representation-learning}
    }
    

    Related Publications

    No related publications found.


    Details
[1]
  1. Relation-Guided Pre-Training for Open-Domain Question Answering

    Ziniu Hu, Yizhou Sun, and Kai-Wei Chang, in EMNLP-Finding, 2021.
    QA Sessions: FINDINGS PAPERS - QUESTION ANSWERING Paper link in the virtual conference
    Full Text BibTeX Details
    Answering complex open-domain questions requires understanding the latent relations between involving entities. However, we found that the existing QA datasets are extremely imbalanced in some types of relations, which hurts the generalization performance over questions with long-tail relations. To remedy this problem, in this paper, we propose a Relation-Guided Pre-Training (RGPT-QA) framework. We first generate a relational QA dataset covering a wide range of relations from both the Wikidata triplets and Wikipedia hyperlinks. We then pre-train a QA model to infer the latent relations from the question, and then conduct extractive QA to get the target answer entity. We demonstrate that by pretraining with propoed RGPT-QA techique, the popular open-domain QA model, Dense Passage Retriever (DPR), achieves 2.2%, 2.4%, and 6.3% absolute improvement in Exact Match accuracy on Natural Questions, TriviaQA, and WebQuestions. Particularly, we show that RGPT-QA improves significantly on questions with long-tail relations
    @inproceedings{hu2021relation,
      title = {Relation-Guided Pre-Training for Open-Domain Question Answering},
      author = {Hu, Ziniu and Sun, Yizhou and Chang, Kai-Wei},
      presentation_id = {https://underline.io/events/192/sessions/7932/lecture/38507-relation-guided-pre-training-for-open-domain-question-answering},
      booktitle = {EMNLP-Finding},
      year = {2021}
    }
    
    Details