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Congliang Chen

9 accepted papers

2026

AdaGC: Enhancing LLM Pretraining Stability via Adaptive Gradient Clipping

ICML 2026poster

Loss spikes remain a persistent obstacle in large-scale language model pretraining. While previous research has attempted to identify the root cause of loss spikes by investigating individual factors, we observe that, in practice, such spikes are typically triggered by the confluence of heterogeneou…

Cited by 0SourceScholar
2026

Knapsack RL: Unlocking Exploration of LLMs via Optimizing Budget Allocation

ICML 2026poster

Large Language Models (LLMs) can improve via reinforcement learning by generating trajectories to discover better solutions. This exploration process represents an investment of finite GPU compute to obtain learning signals. However, current methods typically allocate a small, uniform budget to ever…

Cited by 0SourceScholar
2025

Adam-mini: Use Fewer Learning Rates To Gain More

ICLR 2025poster

We propose Adam-mini, an optimizer that achieves on-par or better performance than AdamW with $50$% less memory footprint. Adam-mini reduces memory by cutting down the learning rate resources in Adam (i.e., $1/\sqrt{v}$). By delving into the Hessian structure of neural nets, we find Adam’s $v$ might…

2025

Preserving Diversity in Supervised Fine-Tuning of Large Language Models

ICLR 2025poster

Large Language Models (LLMs) typically rely on Supervised Fine-Tuning (SFT) to specialize in downstream tasks, with the Cross Entropy (CE) loss being the de facto choice. However, CE maximizes the likelihood of observed data without accounting for alternative possibilities. As such, CE usually lead…

Cited by 0SourcePDFScholar
2024

Unlocking Black-Box Prompt Tuning Efficiency via Zeroth-Order Optimization

EMNLP 2024finding

Prompt optimization emerges as an important technique for adapting Large Language Models (LLMs) to specific tasks. Unfortunately, LLM proprietors often limit access to models’ internal weights, confining users to inference API services. This restriction poses a significant challenge for prompt optim…

2024

Why Transformers Need Adam: A Hessian Perspective

NeurIPS 2024poster

SGD performs worse than Adam by a significant margin on Transformers, but the reason remains unclear. In this work, we provide an explanation through the lens of Hessian: (i) Transformers are "heterogeneous'': the Hessian spectrum across parameter blocks vary dramatically, a phenomenon we call "bloc…

2022

Adam Can Converge Without Any Modification On Update Rules

NeurIPS 2022accept

Ever since \citet{reddi2019convergence} pointed out the divergence issue of Adam, many new variants have been designed to obtain convergence. However, vanilla Adam remains exceptionally popular and it works well in practice. Why is there a gap between theory and practice? We point out there is a mis…

Cited by 98SourcePDFScholar
2021

Communication Efficient Primal-Dual Algorithm for Nonconvex Nonsmooth Distributed Optimization

AISTATS 2021poster

Decentralized optimization problems frequently appear in the large scale machine learning problems. However, few works work on the difficult nonconvex nonsmooth case. In this paper, we propose a decentralized primal-dual algorithm to solve this type of problem in a decentralized manner and the propo…

Cited by 19SourcePDFScholar