Papers by Pengcheng He

27 papers
Query Rewriting in Retrieval-Augmented Large Language Models (2023.emnlp-main)

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Challenge: Existing studies focus on adapting either the retriever or the reader, but this approach is more focused on adaptation of the query itself.
Approach: They propose a new framework for retrieval-augmented Large Language Models . they propose rewrite-retrieve-read instead of retrieve-then-read .
Outcome: The proposed framework improves performance on downstream tasks, open-domain QA and multiple-choice QA.
SILC-EFSA: Self-aware In-context Learning Correction for Entity-level Financial Sentiment Analysis (2025.coling-main)

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Challenge: Currently, most sentiment analysis corpora use sequence-level annotation.
Approach: They propose a two-stage approach to financial entity-level sentiment analysis called Self-aware In-context Learning Correction.
Outcome: The proposed approach achieves state-of-the-art on the largest English and Chinese financial entity-level sentiment analysis datasets to date.
StructVAE: Tree-structured Latent Variable Models for Semi-supervised Semantic Parsing (P18-1)

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Challenge: Semantic parsing is the task of transducing natural language (NL) utterances into formal meaning representations (MRs), commonly represented as tree structures.
Approach: They propose a variational auto-encoding model for semi-supervised semantic parsing which learns from limited amounts of parallel data and readily-available unlabeled NL utterances.
Outcome: Experiments on ATIS domain and Python show that with extra unlabeled data, StructVAE outperforms strong supervised models.
Z-Code++: A Pre-trained Language Model Optimized for Abstractive Summarization (2023.acl-long)

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Challenge: Z-Code++ is a pre-trained language model optimized for abstractive text summarization.
Approach: They propose a pre-trained language model optimized for abstractive text summarization that uses a two-phase pre-training technique to improve model's performance.
Outcome: The proposed model outperforms the competing models on low-resource summarization tasks in zero-shot and few-shot settings.
Adversarial Regularization as Stackelberg Game: An Unrolled Optimization Approach (2021.emnlp-main)

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Challenge: Existing approaches to adversarial regularization treat adversarials and defending players equally, which is undesirable because only the defending player contributes to the generalization performance.
Approach: They propose a method which formulates adversarial regularization as a Stackelberg game and induces a competition between a leader and a follower.
Outcome: The proposed method outperforms existing adversarial regularization baselines on a set of machine translation and natural language understanding tasks.
The Microsoft Toolkit of Multi-Task Deep Neural Networks for Natural Language Understanding (2020.acl-demos)

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Challenge: MT-DNN is an open-source natural language understanding toolkit . it allows researchers and developers to train customized deep learning models .
Approach: They present MT-DNN, an open-source natural language understanding toolkit . it is designed to facilitate rapid customization for a broad spectrum of NLU tasks . MT supports multi-task knowledge distillation, which can substantially compress a deep neural model without significant performance drop.
Outcome: The proposed model can significantly compress a large model without significant performance drop.
Token-wise Curriculum Learning for Neural Machine Translation (2021.findings-emnlp)

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Challenge: Existing curriculum learning approaches to Neural Machine Translation (NMT) require sampling sufficient amounts of “easy” samples from training data at the early stage of training.
Approach: They propose a token-wise curriculum learning approach that creates sufficient amounts of easy samples from training data.
Outcome: The proposed approach outperforms baselines on five language pairs on low-resource languages.
Super Tickets in Pre-Trained Language Models: From Model Compression to Improving Generalization (2021.acl-long)

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Challenge: 'lottery tickets' can be trained to match the performance of a full model . subnetwork training can also outperform random sampled subnetworks of the same size .
Approach: They propose to train a subnetwork of 'lottery tickets' to match the full model's performance.
Outcome: The proposed model outperforms subnetworks of the same size in a phase transition phenomenon . the proposed model improves single task fine-tuning by 0.9 points on BERT-base and 1.0 points on GLUE large .
ARCH: Efficient Adversarial Regularized Training with Caching (2021.findings-emnlp)

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Challenge: Existing approaches to regularize models require generating a perturbation for each sample in each epoch.
Approach: They propose an adversarial regularization method where perturbations are generated and cached once every several epochs.
Outcome: The proposed method significantly eases the computational burden (saves up to 70% of computational time) it produces a notably better (in most of the tasks) or comparable model generalization.
Evaluating the Instruction-Following Robustness of Large Language Models to Prompt Injection (2024.emnlp-main)

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Challenge: Large Language Models (LLMs) have demonstrated exceptional proficiency in instruction-following, making them increasingly integral to various applications.
Approach: They establish a benchmark to evaluate the robustness of instruction-following LLMs against prompt injection attacks, assessing their ability to discern which instructions to follow and which to disregard.
Outcome: The proposed model is overly sensitive to prompt injection attacks, focusing on the latter part of the prompt without fully understanding the context.
Exploiting Structured Knowledge in Text via Graph-Guided Representation Learning (2020.emnlp-main)

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Challenge: Existing methods for integrating knowledge graphs into pre-trained language models have been poorly implemented.
Approach: They propose a self-supervised entity masking scheme that exploits relational knowledge underlying the text.
Outcome: The proposed model achieves improved performance on five benchmarks, including question answering and knowledge base completion.
ALLSH: Active Learning Guided by Local Sensitivity and Hardness (2022.findings-naacl)

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Challenge: Existing studies show that labeling in crowdsourcing annotations is not an annotation artifact but rather a core linguistic phenomenon.
Approach: They propose to retrieve unlabeled data with a local sensitivity and hardness-aware acquisition function.
Outcome: The proposed method achieves consistent gains over the commonly used active learning strategies in various classification tasks.
UnitedQA: A Hybrid Approach for Open Domain Question Answering (2021.acl-long)

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Challenge: Recent work on open-domain question answering focuses on either extractive or generative readers exclusively.
Approach: They propose a hybrid approach to extractive and generative readers that leverages both models.
Outcome: The proposed approach outperforms state-of-the-art models on NaturalQuestions and TriviaQA respectively.
Personalized Abstractive Summarization by Tri-agent Generation Pipeline (2024.findings-eacl)

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Challenge: Existing research shows that large language models do not consistently satisfy users' preferences or expectations.
Approach: They propose a tri-agent generation pipeline that includes a generator, an instructor, and an editor to enhance output personalization.
Outcome: The proposed pipeline generates outputs that better meet user expectations on two abstractive summarization datasets.
DIONYSUS: A Pre-trained Model for Low-Resource Dialogue Summarization (2023.acl-long)

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Challenge: Existing methods for summarizing dialogues lack in taking into account the structure of dialogues and rely heavily on labeled data.
Approach: They propose a pre-trained encoder-decoder model for summarizing dialogues in any new domain.
Outcome: The proposed model outperforms existing methods on six datasets and shows ROUGE scores in zero-shot and few-shot settings.
Generation-Augmented Retrieval for Open-Domain Question Answering (2021.acl-long)

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Challenge: Existing approaches to answer open-domain questions use sparse representations and sparsity.
Approach: They propose a method which augments a query by generating relevant contexts from heuristically discovered contexts without external supervision.
Outcome: The proposed approach outperforms state-of-the-art dense retrieval methods on natural questions and triviaQA datasets.
A Hybrid Neural Network Model for Commonsense Reasoning (D19-60)

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Challenge: a hybrid neural network (HNN) model for commonsense reasoning is proposed . it combines language models and semantic similarity models to achieve new state-of-the-art results .
Approach: They propose a hybrid neural network model for commonsense reasoning . it combines a masked language model and a semantic similarity model .
Outcome: The proposed model outperforms the WNLI, WSC and PDP60 benchmarks on three commonsense reasoning tasks.
MoEBERT: from BERT to Mixture-of-Experts via Importance-Guided Adaptation (2022.naacl-main)

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Challenge: Existing methods for training pre-trained language models have limited practicality due to latency requirements.
Approach: They propose a method that uses a Mixture-of-Experts structure to increase model capacity and inference speed.
Outcome: The proposed method outperforms existing distillation methods on natural language understanding and question answering tasks.
OmniTab: Pretraining with Natural and Synthetic Data for Few-shot Table-based Question Answering (2022.naacl-main)

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Challenge: a table-based question answering system requires complex reasoning and alignment between questions and tables.
Approach: They propose a table-based QA model that consumes both natural and synthetic data . they combine retrieval with masking to pair natural sentences with QA .
Outcome: The proposed model outperforms existing models in few-shot and full settings and on WikiTableQuestions.
Multi-Task Deep Neural Networks for Natural Language Understanding (P19-1)

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Challenge: Existing approaches to learning vector-space representations of text are multitask learning and language model pre-training.
Approach: They propose a multi-task deep neural network (MT-DNN) that leverages cross-task data and incorporates a pre-trained bidirectional transformer language model.
Outcome: The proposed model achieves state-of-the-art on ten NLU tasks and pushes the GLUE benchmark to 82.7% (2.2% absolute improvement)
LMGQS: A Large-scale Dataset for Query-focused Summarization (2023.findings-emnlp)

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Challenge: Lack of large-scale datasets for query-focused summarization hinders model development . lack of data limits the ability of QFS models to train robust neural models .
Approach: They propose to generate a query for each summary sentence in a generic summarization annotation using a pretrained language model.
Outcome: The proposed model achieves state-of-the-art zero-shot and supervised performance on multiple existing QFS benchmarks.
CAMERO: Consistency Regularized Ensemble of Perturbed Language Models with Weight Sharing (2022.acl-long)

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Challenge: Existing work has resorted to sharing weights among models, but results are not affordable for real-world deployment.
Approach: They propose a consistency-regularized ensemble learning approach based on perturbed models to retain ensemble benefits while maintaining a low memory cost.
Outcome: The proposed approach outperforms the standard ensemble of 8 BERT-base models on the GLUE benchmark by 0.7 with a significantly smaller model size.
PROM: A Phrase-level Copying Mechanism with Pre-training for Abstractive Summarization (2024.lrec-main)

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Challenge: Existing summarization strategies are abstractive and extractive, but are hard to control.
Approach: They propose a PhRase-level cOpying Mechanism that enhances attention on n-grams and calculates an auxiliary loss for the copying prediction.
Outcome: Empirical studies show that PROM improves copying accuracy and faithfulness on benchmarks.
SMART: Robust and Efficient Fine-Tuning for Pre-trained Natural Language Models through Principled Regularized Optimization (2020.acl-main)

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Challenge: Existing methods for fine-tuning pre-trained models fail to generalize to unseen data.
Approach: They propose a framework for robust and efficient fine-tuning for pre-trained models . proposed framework achieves new state-of-the-art performance on a number of NLP tasks .
Outcome: The proposed framework outperforms the state-of-the-art T5 model on GLUE, SNLI, SciTail and ANLI.
EMO-RL: Emotion-Rule-Based Reinforcement Learning Enhanced Audio-Language Model for Generalized Speech Emotion Recognition (2025.findings-emnlp)

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Challenge: Recent advances in reinforcement learning (RL) have shown promise in improving LALMs’ reasoning abilities, but their performance in affective computing tasks remains suboptimal.
Approach: They propose a framework incorporating reinforcement learning with two key innovations: Emotion Similarity-Weighted Reward (ESWR) and Explicit Structured Reasoning (ESR).
Outcome: The proposed framework improves LALMs' reasoning abilities on MELD and IEMOCAP datasets and shows strong generalization.
ContextCheck: Sentence-Level Faithfulness Verification with Context-Aware Disambiguation (2026.findings-acl)

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Challenge: Large language models often hallucinate, producing content that is factually incorrect or not grounded in the sources.
Approach: They propose a framework for sentence-level faithfulness verification with context-aware disambiguation.
Outcome: The proposed framework improves Macro F1 by over 10 points compared to baselines on three context-dependent datasets.
Reader-Guided Passage Reranking for Open-Domain Question Answering (2021.findings-acl)

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Challenge: Current open-domain question answering systems follow a Retriever-Reader architecture . current systems do not use a reranker, which reranked passages based on top predictions of the reader .
Approach: They propose a reader-guIDEd reranking method that reranked passages based on top predictions . they show that RIDER achieves 10 to 20 absolute gains in top-1 retrieval accuracy .
Outcome: The proposed method achieves 10 to 20 gains in top-1 retrieval accuracy and 1 to 4 Exact Match gains without training.

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