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Zhiyuan Fan

21 accepted papers

2026

Diversity-Enhanced Reasoning for Subjective Questions

ICLR 2026poster

Large Reasoning Models (LRMs) with long chain-of-thought capabilities, optimized via reinforcement learning with verifiable rewards (RLVR), excel at **objective reasoning** tasks like mathematical problem solving and code generation. However, RLVR is known for degrading generation diversity, which c…

Cited by 0SourcecodeScholar
2026

Online Learning and Equilibrium Computation with Ranking Feedback

ICLR 2026oral

Online learning in arbitrary and possibly adversarial environments has been extensively studied in sequential decision-making, with a strong connection to equilibrium computation in game theory. Most existing online learning algorithms are based on \emph{numeric} utility feedback from the environmen…

Cited by 0SourceScholar
2026

Tackling Length Inflation Without Trade-offs: Group Relative Reward Rescaling for Reinforcement Learning

ICML 2026poster

Reinforcement learning significantly enhances LLM capabilities but suffers from a critical issue: length inflation, where models adopt verbosity or inefficient reasoning to maximize rewards. Prior approaches struggle to address this challenge in a general and lossless manner, primarily because addit…

Cited by 0SourceScholar
2026

Towards Self-Evolving Agent Benchmarks : Validatable Agent Trajectory via Test-Time Exploration

ICLR 2026poster

Recent advances in large language models (LLMs) and agent system designs have empowered agents with unprecedented levels of capability. However, existing agent benchmarks are showing a trend of rapid ceiling-hitting by newly developed agents, making it difficult to meet the demands for evaluating ag…

Cited by 0SourcecodeScholar
2025

CALM: Unleashing the Cross-Lingual Self-Aligning Ability of Language Model Question Answering

NAACL 2025findings

Large Language Models (LLMs) are pretrained on extensive multilingual corpora to acquire both language-specific cultural knowledge and general knowledge. Ideally, while LLMs should provide consistent responses to culture-independent questions across languages, we observe significant performance disp…

2025

End-to-End Optimization for Multimodal Retrieval-Augmented Generation via Reward Backpropagation

EMNLP 2025

Multimodal Retrieval-Augmented Generation (MM-RAG) has emerged as a promising approach for enhancing the reliability and factuality of large vision-language models (LVLMs). While end-to-end loss backpropagation is infeasible due to non-differentiable operations during the forward process, current me

2025

MMBoundary: Advancing MLLM Knowledge Boundary Awareness through Reasoning Step Confidence Calibration

ACL 2025long

In recent years, multimodal large language models (MLLMs) have made significant progress but continue to face inherent challenges in multimodal reasoning, which requires multi-level (e.g., perception, reasoning) and multi-granular (e.g., multi-step reasoning chain) advanced inferencing. Prior work o…

2025

MedEBench: Diagnosing Reliability in Text-Guided Medical Image Editing

EMNLP 2025

Text-guided image editing has seen significant progress in natural image domains, but its application in medical imaging remains limited and lacks standardized evaluation frameworks. Such editing could revolutionize clinical practices by enabling personalized surgical planning, enhancing medical edu

Cited by 0SourcePDFScholar
2025

On the Universal Near Optimality of Hedge in Combinatorial Settings

NeurIPS 2025spotlight

In this paper, we study the classical Hedge algorithm in combinatorial settings. In each round, the learner selects a vector $\mathbf{x}_t$ from a set $\mathcal{X} \subseteq$ {$0,1$}$^d$, observes a full loss vector $\mathbf{y}_t \in \mathbb{R}^d$, and incurs a loss $\langle \mathbf{x}_t, \mathbf{y}…

Cited by 0SourceScholar
2025

SHARP: Unlocking Interactive Hallucination via Stance Transfer in Role-Playing LLMs

ACL 2025finding

The advanced role-playing capabilities of Large Language Models (LLMs) have enabled rich interactive scenarios, yet existing research in social interactions neglects hallucination while struggling with poor generalizability and implicit character fidelity judgments. To bridge this gap, motivated by…

Cited by 0SourcePDFScholar
2025

Unveiling the Lack of LVLM Robustness to Fundamental Visual Variations: Why and Path Forward

ACL 2025finding

Large Vision Language Models (LVLMs) have shown impressive performance on various vision-language tasks. However, while objects in natural scenes inevitably exhibit visual variations in position, scale, orientation, and context due to changes in viewpoint and environment, the robustness of LVLMs to…

2024

Achieving Constant Regret in Linear Markov Decision Processes

NeurIPS 2024poster

We study the constant regret guarantees in reinforcement learning (RL). Our objective is to design an algorithm that incurs only finite regret over infinite episodes with high probability. We introduce an algorithm, Cert-LSVI-UCB, for misspecified linear Markov decision processes (MDPs) where both t…

Cited by 0SourcePDFScholar
2024

CARES: A Comprehensive Benchmark of Trustworthiness in Medical Vision Language Models

NeurIPS 2024poster

Artificial intelligence has significantly impacted medical applications, particularly with the advent of Medical Large Vision Language Models (Med-LVLMs), sparking optimism for the future of automated and personalized healthcare. However, the trustworthiness of Med-LVLMs remains unverified, posing s…

2024

Calibrated Self-Rewarding Vision Language Models

NeurIPS 2024poster

Large Vision-Language Models (LVLMs) have made substantial progress by integrating pre-trained large language models (LLMs) and vision models through instruction tuning. Despite these advancements, LVLMs often exhibit the hallucination phenomenon, where generated text responses appear linguistically…

2024

On the Optimality of Dilated Entropy and Lower Bounds for Online Learning in Extensive-Form Games

NeurIPS 2024poster

First-order methods (FOMs) are arguably the most scalable algorithms for equilibrium computation in large extensive-form games. To operationalize these methods, a distance-generating function, acting as a regularizer for the strategy space, must be chosen. The ratio between the strong convexity mod…

Cited by 1SourcePDFScholar
2024

SedarEval: Automated Evaluation using Self-Adaptive Rubrics

EMNLP 2024finding

The evaluation paradigm of LLM-as-judge gains popularity due to its significant reduction in human labor and time costs. This approach utilizes one or more large language models (LLMs) to assess the quality of outputs from other LLMs. However, existing methods rely on generic scoring rubrics that fa…

2023

Efficient Data Learning for Open Information Extraction with Pre-trained Language Models

EMNLP 2023short findings

Open Information Extraction (OpenIE) is a fundamental yet challenging task in Natural Language Processing, which involves extracting all triples (subject, predicate, object) from a given sentence. While labelling-based methods have their merits, generation-based techniques offer unique advantages, s…

Cited by 0SourceScholar
2023

On the Interplay Between Misspecification and Sub-optimality Gap in Linear Contextual Bandits

ICML 2023poster

We study linear contextual bandits in the misspecified setting, where the expected reward function can be approximated by a linear function class up to a bounded misspecification level $\zeta>0$. We propose an algorithm based on a novel data selection scheme, which only selects the contextual vector…

Cited by 9SourcePDFScholar
2023

OpenFE: Automated Feature Generation with Expert-level Performance

ICML 2023poster

The goal of automated feature generation is to liberate machine learning experts from the laborious task of manual feature generation, which is crucial for improving the learning performance of tabular data. The major challenge in automated feature generation is to efficiently and accurately identif…

Cited by 32SourcePDFScholar