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Pengcheng He

40 accepted papers

2026

Koopman-Assisted Trajectory Synthesis: A Data Augmentation Framework for Offline Imitation Learning

ICLR 2026poster

Data augmentation plays a pivotal role in offline imitation learning (IL) by alleviating covariate shift, yet existing methods remain constrained. Single-step techniques frequently violate underlying system dynamics, whereas trajectory-level approaches are plagued by compounding errors or scalabilit…

Cited by 0SourceScholar
2026

ThetaEvolve: Test-time Learning on Open Problems

ICML 2026poster

Recent advances in large language models (LLMs) have enabled breakthroughs in mathematical discovery, exemplified by AlphaEvolve, a closed-source system that evolves programs to improve bounds on open problems. However, it relies on ensembles of frontier LLMs to achieve new bounds and is a pure infe…

Cited by 0SourceScholar
2025

Deep Reinforcement Learning from Hierarchical Preference Design

ICML 2025poster

Reward design is a fundamental, yet challenging aspect of reinforcement learning (RL). Researchers typically utilize feedback signals from the environment to handcraft a reward function, but this process is not always effective due to the varying scale and intricate dependencies of the feedback sign…

2024

DoLa: Decoding by Contrasting Layers Improves Factuality in Large Language Models

ICLR 2024poster

Despite their impressive capabilities, large language models (LLMs) are prone to hallucinations, i.e., generating content that deviates from facts seen during pretraining. We propose a simple decoding strategy for reducing hallucinations with pretrained LLMs that does not require conditioning on ret…

2024

Evaluating the Instruction-Following Robustness of Large Language Models to Prompt Injection

EMNLP 2024main

Large Language Models (LLMs) have demonstrated exceptional proficiency in instruction-following, making them increasingly integral to various applications. However, this capability introduces the risk of prompt injection attacks, where malicious instructions are embedded in the input to trigger unin…

2024

Learning Stackable and Skippable LEGO Bricks for Efficient, Reconfigurable, and Variable-Resolution Diffusion Modeling

ICLR 2024poster

Diffusion models excel at generating photo-realistic images but come with significant computational costs in both training and sampling. While various techniques address these computational challenges, a less-explored issue is designing an efficient and adaptable network backbone for iterative refin…

2024

LoftQ: LoRA-Fine-Tuning-aware Quantization for Large Language Models

ICLR 2024oral

Quantization is an indispensable technique for serving Large Language Models (LLMs) and has recently found its way into LoRA fine-tuning (Dettmers et al., 2023). In this work we focus on the scenario where quantization and LoRA fine- tuning are applied together on a pre-trained model. In such cases…

2024

PROM: A Phrase-level Copying Mechanism with Pre-training for Abstractive Summarization

COLING 2024main

Based on the remarkable achievements of pre-trained language models in abstractive summarization, the copying mechanism has proved helpful by improving the factuality, stability, and overall performance. This work proposes PROM, a new PhRase-level cOpying Mechanism that enhances attention on n-grams…

2024

Seeking Neural Nuggets: Knowledge Transfer in Large Language Models from a Parametric Perspective

ICLR 2024poster

Large Language Models (LLMs) inherently encode a wealth of knowledge within their parameters through pre-training on extensive corpora. While prior research has delved into operations on these parameters to manipulate the underlying implicit knowledge — encompassing detection, editing, and merging —…

2024

Switchable Decision: Dynamic Neural Generation Networks

ICML 2024poster

Auto-regressive generation models achieve competitive performance across many different NLP tasks such as summarization, question answering, and classifications. However, they are also known for being slow in inference, which makes them challenging to deploy in real-time applications. We propose a s…

Cited by 0SourcePDFScholar
2023

Adaptive Budget Allocation for Parameter-Efficient Fine-Tuning

ICLR 2023poster

Fine-tuning large pre-trained language models on downstream tasks has become an important paradigm in NLP. However, common practice fine-tunes all of the parameters in a pre-trained model, which becomes prohibitive when a large number of downstream tasks are present. Therefore, many fine-tuning meth…

2023

DIONYSUS: A Pre-trained Model for Low-Resource Dialogue Summarization

ACL 2023long

Dialogue summarization has recently garnered significant attention due to its wide range of applications. However, existing methods for summarizing dialogues have limitations because they do not take into account the inherent structure of dialogue and rely heavily on labeled data, which can lead to…

2023

DeBERTaV3: Improving DeBERTa using ELECTRA-Style Pre-Training with Gradient-Disentangled Embedding Sharing

ICLR 2023poster

This paper presents a new pre-trained language model, NewModel, which improves the original DeBERTa model by replacing mask language modeling (MLM) with replaced token detection (RTD), a more sample-efficient pre-training task. Our analysis shows that vanilla embedding sharing in ELECTRA hurts train…

2023

Diffusion-GAN: Training GANs with Diffusion

ICLR 2023poster

Generative adversarial networks (GANs) are challenging to train stably, and a promising remedy of injecting instance noise into the discriminator input has not been very effective in practice. In this paper, we propose Diffusion-GAN, a novel GAN framework that leverages a forward diffusion chain to…

2023

Guiding Large Language Models via Directional Stimulus Prompting

NeurIPS 2023poster

We introduce Directional Stimulus Prompting, a novel framework for guiding black-box large language models (LLMs) towards specific desired outputs. Instead of directly adjusting LLMs, our method employs a small tunable policy model (e.g., T5) to generate an auxiliary directional stimulus prompt for…

2023

HyperTuning: Toward Adapting Large Language Models without Back-propagation

ICML 2023poster

Fine-tuning large language models for different tasks can be costly and inefficient, and even methods that reduce the number of tuned parameters still require full gradient-based optimization. We propose HyperTuning, a novel approach to model adaptation that uses a hypermodel to generate task-specif…

Cited by 34SourcePDFScholar
2023

In-Context Learning Unlocked for Diffusion Models

NeurIPS 2023spotlight

We present Prompt Diffusion, a framework for enabling in-context learning in diffusion-based generative models. Given a pair of task-specific example images, such as depth from/to image and scribble from/to image, and a text guidance, our model automatically understands the underlying task and perfo…

2023

LMGQS: A Large-scale Dataset for Query-focused Summarization

EMNLP 2023long findings

Query-focused summarization (QFS) aims to extract or generate a summary of an input document that directly answers or is relevant to a given query. The lack of large-scale datasets in the form of documents, queries, and summaries has hindered model development in this area. In contrast, multiple lar…

Cited by 0SourceScholar
2023

Less is More: Task-aware Layer-wise Distillation for Language Model Compression

ICML 2023poster

Layer-wise distillation is a powerful tool to compress large models (i.e. teacher models) into small ones (i.e., student models). The student distills knowledge from the teacher by mimicking the hidden representations of the teacher at every intermediate layer. However, layer-wise distillation is di…

2023

LoSparse: Structured Compression of Large Language Models based on Low-Rank and Sparse Approximation

ICML 2023poster

Transformer models have achieved remarkable results in various natural language tasks, but they are often prohibitively large, requiring massive memories and computational resources. To re- duce the size and complexity of these models, we propose LoSparse (Low-Rank and Sparse ap- proximation), a nov…

2023

POUF: Prompt-Oriented Unsupervised Fine-tuning for Large Pre-trained Models

ICML 2023poster

Through prompting, large-scale pre-trained models have become more expressive and powerful, gaining significant attention in recent years. Though these big models have zero-shot capabilities, in general, labeled data are still required to adapt them to downstream tasks. To overcome this critical lim…

2023

Patch Diffusion: Faster and More Data-Efficient Training of Diffusion Models

NeurIPS 2023poster

Diffusion models are powerful, but they require a lot of time and data to train. We propose Patch Diffusion, a generic patch-wise training framework, to significantly reduce the training time costs while improving data efficiency, which thus helps democratize diffusion model training to broader user…

2023

Truncated Diffusion Probabilistic Models and Diffusion-based Adversarial Auto-Encoders

ICLR 2023poster

Employing a forward diffusion chain to gradually map the data to a noise distribution, diffusion-based generative models learn how to generate the data by inferring a reverse diffusion chain. However, this approach is slow and costly because it needs many forward and reverse steps. We propose a fas…

2023

Z-Code++: A Pre-trained Language Model Optimized for Abstractive Summarization

ACL 2023long

This paper presents Z-Code++, a new pre-trained language model optimized for abstractive text summarization. The model extends the state-of-the-art encoder-decoder model using three techniques. First, we use a two-phase pre-training to improve the model’s performance on low-resource summarization ta…

2022

ALLSH: Active Learning Guided by Local Sensitivity and Hardness

NAACL 2022findings

Active learning, which effectively collects informative unlabeled data for annotation, reduces the demand for labeled data. In this work, we propose to retrieve unlabeled samples with a local sensitivity and hardness-aware acquisition function. The proposed method generates data copies through local…

Cited by 39SourcePDFScholar
2022

CAMERO: Consistency Regularized Ensemble of Perturbed Language Models with Weight Sharing

ACL 2022long

Model ensemble is a popular approach to produce a low-variance and well-generalized model. However, it induces large memory and inference costs, which is often not affordable for real-world deployment. Existing work has resorted to sharing weights among models. However, when increasing the proportio…

2022

Human Parity on CommonsenseQA: Augmenting Self-Attention with External Attention

IJCAI 2022poster

Most of today's AI systems focus on using self-attention mechanisms and transformer architectures on large amounts of diverse data to achieve impressive performance gains. In this paper, we propose to augment the transformer architecture with an external attention mechanism to bring external knowled…

2022

MoEBERT: from BERT to Mixture-of-Experts via Importance-Guided Adaptation

NAACL 2022long

Pre-trained language models have demonstrated superior performance in various natural language processing tasks. However, these models usually contain hundreds of millions of parameters, which limits their practicality because of latency requirements in real-world applications. Existing methods trai…

2022

No Parameters Left Behind: Sensitivity Guided Adaptive Learning Rate for Training Large Transformer Models

ICLR 2022poster

Recent research has shown the existence of significant redundancy in large Transformer models. One can prune the redundant parameters without significantly sacrificing the generalization performance. However, we question whether the redundant parameters could have contributed more if they were prope…

2022

OmniTab: Pretraining with Natural and Synthetic Data for Few-shot Table-based Question Answering

NAACL 2022long

The information in tables can be an important complement to text, making table-based question answering (QA) systems of great value. The intrinsic complexity of handling tables often adds an extra burden to both model design and data annotation. In this paper, we aim to develop a simple table-based…

2022

PLATON: Pruning Large Transformer Models with Upper Confidence Bound of Weight Importance

ICML 2022spotlight

Large Transformer-based models have exhibited superior performance in various natural language processing and computer vision tasks. However, these models contain enormous amounts of parameters, which restrict their deployment to real-world applications. To reduce the model size, researchers prune t…

2021

ARCH: Efficient Adversarial Regularized Training with Caching

EMNLP 2021finding

Adversarial regularization can improve model generalization in many natural language processing tasks. However, conventional approaches are computationally expensive since they need to generate a perturbation for each sample in each epoch. We propose a new adversarial regularization method ARCH (adv…

2021

Adversarial Regularization as Stackelberg Game: An Unrolled Optimization Approach

EMNLP 2021main

Adversarial regularization has been shown to improve the generalization performance of deep learning models in various natural language processing tasks. Existing works usually formulate the method as a zero-sum game, which is solved by alternating gradient descent/ascent algorithms. Such a formulat…

2021

DEBERTA: DECODING-ENHANCED BERT WITH DISENTANGLED ATTENTION

ICLR 2021poster

Recent progress in pre-trained neural language models has significantly improved the performance of many natural language processing (NLP) tasks. In this paper we propose a new model architecture DeBERTa (Decoding-enhanced BERT with disentangled attention) that improves the BERT and RoBERTa models u…

Cited by 3296SourcecodeScholar
2021

Generation-Augmented Retrieval for Open-Domain Question Answering

ACL 2021long

We propose Generation-Augmented Retrieval (GAR) for answering open-domain questions, which augments a query through text generation of heuristically discovered relevant contexts without external resources as supervision. We demonstrate that the generated contexts substantially enrich the semantics o…

2021

Super Tickets in Pre-Trained Language Models: From Model Compression to Improving Generalization

ACL 2021long

The Lottery Ticket Hypothesis suggests that an over-parametrized network consists of ”lottery tickets”, and training a certain collection of them (i.e., a subnetwork) can match the performance of the full model. In this paper, we study such a collection of tickets, which is referred to as ”winning t…

2021

Token-wise Curriculum Learning for Neural Machine Translation

EMNLP 2021finding

Existing curriculum learning approaches to Neural Machine Translation (NMT) require sampling sufficient amounts of “easy” samples from training data at the early training stage. This is not always achievable for low-resource languages where the amount of training data is limited. To address such a l…

2021

UnitedQA: A Hybrid Approach for Open Domain Question Answering

ACL 2021long

To date, most of recent work under the retrieval-reader framework for open-domain QA focuses on either extractive or generative reader exclusively. In this paper, we study a hybrid approach for leveraging the strengths of both models. We apply novel techniques to enhance both extractive and generati…

Cited by 54SourcePDFScholar
2020

On the Variance of the Adaptive Learning Rate and Beyond

ICLR 2020poster

The learning rate warmup heuristic achieves remarkable success in stabilizing training, accelerating convergence and improving generalization for adaptive stochastic optimization algorithms like RMSprop and Adam. Pursuing the theory behind warmup, we identify a problem of the adaptive learning rate…

Cited by 2552SourcecodeScholar