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Licheng Pan

8 accepted papers

2026

DistDF: Time-series Forecasting Needs Joint-distribution Wasserstein Alignment

ICLR 2026poster

Training time-series forecast models requires aligning the conditional distribution of model forecasts with that of the label sequence. The standard direct forecast (DF) approach seeks to minimize the conditional negative log-likelihood of the label sequence, typically estimated using the mean squa…

Cited by 0SourcecodeScholar
2026

Inducing Overthink: Hierarchical Genetic Algorithm-based DoS Attack on Black-Box Reasoning Models

ICML 2026poster

Large Reasoning Models (LRMs) are increasingly integrated into systems requiring reliable multi-step inference, yet this growing dependence exposes new vulnerabilities related to computational availability. In particular, LRMs exhibit a tendency to “overthink’’—producing excessively long and redunda…

Cited by 0SourceScholar
2026

Optimal Transport for Reward Modeling from Noisy Feedback

ICML 2026poster

Reward models are fundamental to Reinforcement Learning from Human Feedback (RLHF), yet real-world datasets are inevitably corrupted by noisy preference. Conventional training objectives tend to overfit these errors, while existing denoising approaches often rely on homogeneous noise assumptions tha…

Cited by 0SourceScholar
2026

Quadratic Direct Forecast for Training Multi-Step Time-Series Forecast Models

ICLR 2026poster

The design of training objective is central to training time-series forecasting models. Existing training objectives such as mean squared error mostly treat each future step as an independent, equally weighted task, which we found leading to the following two issues: (1) overlook the *label autocorr…

Cited by 0SourceScholar
2026

Unbiased Reward Modeling from Implicit Preference

ICML 2026poster

Despite the success of reinforcement learning from human feedback (RLHF) in aligning language models, current reward modeling heavily relies on explicit preference data with high collection costs. In this work, we study implicit reward modeling---learning reward models from implicit human feedback--…

Cited by 0SourceScholar
2025

Time-o1: Time-Series Forecasting Needs Transformed Label Alignment

NeurIPS 2025poster

Training time-series forecast models presents unique challenges in designing effective learning objectives. Existing methods predominantly utilize the temporal mean squared error, which faces two critical challenges: (1) label autocorrelation, which leads to bias from the label sequence likelihood;…

Cited by 0SourcecodeScholar
2025

Unbiased Recommender Learning from Implicit Feedback via Weakly Supervised Learning

ICML 2025poster

Implicit feedback recommendation is challenged by the missing negative feedback essential for effective model training. Existing methods often resort to negative sampling, a technique that assumes unlabeled interactions as negative samples. This assumption risks misclassifying potential positive sam…

2025

Understanding and Mitigating Overrefusal in LLMs from an Unveiling Perspective of Safety Decision Boundary

EMNLP 2025

Large language models (LLMs) have demonstrated remarkable capabilities across a wide range of tasks, yet they often refuse to answer legitimate queries—a phenomenon known as overrefusal. Overrefusal typically stems from over-conservative safety alignment, causing models to treat many reasonable prom