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Ximing Lu

53 accepted papers

2026

BroRL: Scaling Reinforcement Learning via Broadened Exploration

ICML 2026poster

Reinforcement Learning with Verifiable Rewards (RLVR) has emerged as a key ingredient for unlocking complex reasoning capabilities in large language models. Recent work ProRL \citep{liu2025prorl} has shown promise in scaling RL by increasing the number of training steps. However, performance plateau…

Cited by 0SourceScholar
2026

DeepSearch: Overcome the Bottleneck of Reinforcement Learning with Verifiable Rewards via Monte Carlo Tree Search

ICLR 2026poster

Although Reinforcement Learning with Verifiable Rewards (RLVR) has become an essential component for developing advanced reasoning skills in language models, contemporary studies have documented training plateaus that emerge following thousands of optimization steps, demonstrating notable decreases…

Cited by 0SourcecodeScholar
2026

GDPO: Group reward-Decoupled Normalization Policy Optimization for Multi-reward RL Optimization

ICML 2026poster

As language models become increasingly capable, users expect them to provide not only accurate responses but also behaviors aligned with diverse human preferences across a variety of scenarios. To achieve this, Reinforcement learning (RL) pipelines have begun incorporating multiple rewards, each cap…

Cited by 0SourceScholar
2026

Goedel-Prover-V2: Scaling Formal Theorem Proving with Scaffolded Data Synthesis and Self-Correction

ICLR 2026poster

Automated theorem proving (ATP) --- the task of generating a proof that passes automated proof verification given a math question in formal language --- is a critical challenge at the intersection of mathematics and Artificial Intelligence (AI). We introduce Goedel-Prover-V2, a family of two languag…

Cited by 0SourcecodeScholar
2026

Golden Goose: A Simple Trick to Synthesize Unlimited RLVR Tasks from Unverifiable Internet Text

ICML 2026poster

Reinforcement Learning with Verifiable Rewards (RLVR) has become a cornerstone for unlocking complex reasoning in Large Language Models (LLMs). Yet, scaling up RL is bottlenecked by limited existing verifiable data, where improvements increasingly saturate over prolonged training. To overcome this, …

Cited by 0SourceScholar
2026

Long Grounded Thoughts: Synthesizing Grounded Visual Problems and Distilling Reasoning Chains at Scale

ICML 2026poster

Despite rapid progress, multimodal reasoning still lacks a systematic approach to synthesize large-scale vision-centric datasets beyond visual math. We introduce a framework able to synthesize vision-centric problems spanning diverse levels of complexity, and the resulting dataset with over 1M high-…

Cited by 0SourceScholar
2026

ProfBench: Multi-Domain Rubrics requiring Professional Knowledge to Answer and Judge

ICLR 2026poster

Evaluating progress in large language models (LLMs) is often constrained by the challenge of verifying responses, limiting assessments to tasks like mathematics, programming, and short-form question-answering. However, many real-world applications require evaluating LLMs in processing professional d…

Cited by 0SourcecodeScholar
2026

ToolOrchestra: Elevating Intelligence via Efficient Model and Tool Orchestration

ICML 2026poster

Large language models are powerful generalists, yet solving deep and complex problems such as those of the Humanity’s Last Exam (HLE) remains both conceptually challenging and computationally expensive. We show that small orchestrators managing other models and a variety of tools are able to both pu…

Cited by 0SourceScholar
2025

AI as Humanity’s Salieri: Quantifying Linguistic Creativity of Language Models via Systematic Attribution of Machine Text against Web Text

ICLR 2025oral

Creativity has long been considered one of the most difficult aspect of human intelligence for AI to mimic. However, the rise of Large Language Models (LLMs), like ChatGPT, has raised questions about whether AI can match or even surpass human creativity. We present CREATIVITY INDEX as the first step…

2025

Bias in Gender Bias Benchmarks: How Spurious Features Distort Evaluation

ICCV 2025poster

Gender bias in vision-language foundation models (VLMs) raises concerns about their safe deployment and is typically evaluated using benchmarks with gender annotations on real-world images. However, as these benchmarks often contain spurious correlations between gender and non-gender features, such…

Cited by 0SourcePDFScholar
2025

CertainlyUncertain: A Benchmark and Metric for Multimodal Epistemic and Aleatoric Awareness

ICLR 2025poster

The ability to acknowledge the inevitable uncertainty in their knowledge and reasoning is a prerequisite for AI systems to be truly truthful and reliable. In this paper, we present a taxonomy of uncertainty specific to vision-language AI systems, distinguishing between epistemic uncertainty (arising…

Cited by 1SourcePDFScholar
2025

Information-Guided Identification of Training Data Imprint in (Proprietary) Large Language Models

NAACL 2025long

High-quality training data has proven crucial for developing performant large language models (LLMs). However, commercial LLM providers disclose few, if any, details about the data used for training. This lack of transparency creates multiple challenges: it limits external oversight and inspection o…

Cited by 1SourcePDFScholar
2025

Prismatic Synthesis: Gradient-based Data Diversification Boosts Generalization in LLM Reasoning

NeurIPS 2025spotlight

Data diversity is crucial for training a strong language model. Yet metrics of diversity often diverge from this goal, measuring variations in heuristic features—like n-grams or embeddings—that are detached from how the model actually performs on a target task. This motivates us to ask: *Can we rede…

Cited by 0SourceScholar
2025

ProRL: Prolonged Reinforcement Learning Expands Reasoning Boundaries in Large Language Models

NeurIPS 2025poster

Recent advances in reasoning-centric language models have highlighted reinforcement learning (RL) as a promising method for aligning models with verifiable rewards. However, it remains contentious whether RL truly expands a model’s reasoning capabilities or merely amplifies high-reward outputs alrea…

Cited by 0SourcecodeScholar
2025

Socratic-MCTS: Test-Time Visual Reasoning by Asking the Right Questions

EMNLP 2025

Recent research in vision-language models (VLMs) has centered around the possibility of equipping them with implicit long-form chain-of-thought reasoning—akin to the success observed in language models—via distillation and reinforcement learning. But what about the non-reasoning models already train

Cited by 0SourcePDFScholar
2024

How to Train Your Fact Verifier: Knowledge Transfer with Multimodal Open Models

EMNLP 2024finding

Given the growing influx of misinformation across news and social media, there is a critical need for systems that can provide effective real-time verification of news claims. Large language or multimodal model based verification has been proposed to scale up online policing mechanisms for mitigatin…

Cited by 0SourcePDFScholar
2024

Impossible Distillation for Paraphrasing and Summarization: How to Make High-quality Lemonade out of Small, Low-quality Model

NAACL 2024long

We present Impossible Distillation, a novel framework for paraphrasing and sentence summarization, that distills a high-quality dataset and model from a low-quality teacher that itself cannot perform these tasks. Unlike prior works that rely on an extreme-scale teacher model (e.g., GPT3) or task-spe…

Cited by 1SourcePDFScholar
2024

In Search of the Long-Tail: Systematic Generation of Long-Tail Inferential Knowledge via Logical Rule Guided Search

EMNLP 2024main

To effectively use large language models (LLMs) for real-world queries, it is imperative that they generalize to the long-tail distribution, i.e. rare examples where models exhibit low confidence. In this work, we take the first step towards evaluating LLMs in the long-tail distribution of inferenti…

2024

JAMDEC: Unsupervised Authorship Obfuscation using Constrained Decoding over Small Language Models

NAACL 2024long

The permanence of online content combined with the enhanced authorship identification techniques calls for stronger computational methods to protect the identity and privacy of online authorship when needed, e.g., blind reviews for scientific papers, anonymous online reviews, or anonymous interactio…

2024

Leftover Lunch: Advantage-based Offline Reinforcement Learning for Language Models

ICLR 2024poster

Reinforcement Learning with Human Feedback (RLHF) is the most prominent method for Language Model (LM) alignment. However, RLHF is an unstable and data-hungry process that continually requires new high-quality LM-generated data for finetuning. We introduce Advantage-Leftover Lunch RL (A-LoL), a new…

2024

Phenomenal Yet Puzzling: Testing Inductive Reasoning Capabilities of Language Models with Hypothesis Refinement

ICLR 2024oral

The ability to derive underlying principles from a handful of observations and then generalize to novel situations---known as inductive reasoning---is central to human intelligence. Prior work suggests that language models (LMs) often fall short on inductive reasoning, despite achieving impressive s…

2024

Position: A Roadmap to Pluralistic Alignment

ICML 2024poster

With increased power and prevalence of AI systems, it is ever more critical that AI systems are designed to serve *all*, i.e., people with diverse values and perspectives. However, aligning models to serve *pluralistic* human values remains an open research question. In this piece, we propose a road…

Cited by 0SourcePDFScholar
2024

StyleRemix: Interpretable Authorship Obfuscation via Distillation and Perturbation of Style Elements

EMNLP 2024main

Authorship obfuscation, rewriting a text to intentionally obscure the identity of the author, is important yet challenging. Current methods using large language models (LLMs) lack interpretability and controllability, often ignoring author-specific stylistic features, resulting in less robust perfor…

2024

Tailoring Self-Rationalizers with Multi-Reward Distillation

ICLR 2024poster

Large language models (LMs) are capable of generating free-text rationales to aid question answering. However, prior work 1) suggests that useful self-rationalization is emergent only at significant scales (e.g., 175B parameter GPT-3); and 2) focuses largely on downstream performance, ignoring the s…

2024

The Generative AI Paradox: “What It Can Create, It May Not Understand”

ICLR 2024poster

The recent wave of generative AI has sparked unprecedented global attention, with both excitement and concern over potentially superhuman levels of artificial intelligence: models now take only seconds to produce outputs that would challenge or exceed the capabilities even of expert humans. At the s…

Cited by 30SourcePDFScholar
2024

The Unlocking Spell on Base LLMs: Rethinking Alignment via In-Context Learning

ICLR 2024poster

Alignment tuning has become the de facto standard practice for enabling base large language models (LLMs) to serve as open-domain AI assistants. The alignment tuning process typically involves instruction learning through supervised fine-tuning (SFT) and preference tuning via reinforcement learning…

Cited by 169SourcePDFScholar
2024

Value Kaleidoscope: Engaging AI with Pluralistic Human Values, Rights, and Duties

AAAI 2024technical

Human values are crucial to human decision-making. Value pluralism is the view that multiple correct values may be held in tension with one another (e.g., when considering lying to a friend to protect their feelings, how does one balance honesty with friendship?). As statistical learners, AI systems…

2024

WildTeaming at Scale: From In-the-Wild Jailbreaks to (Adversarially) Safer Language Models

NeurIPS 2024poster

We introduce WildTeaming, an automatic red-teaming framework that mines in-the-wild user-chatbot interactions to discover 5.7K unique clusters of novel jailbreak tactics, and then composes selections of multiple mined tactics for systematic exploration of novel and even more challenging jailbreaks.…

2023

ClarifyDelphi: Reinforced Clarification Questions with Defeasibility Rewards for Social and Moral Situations

ACL 2023long

Context is everything, even in commonsense moral reasoning. Changing contexts can flip the moral judgment of an action; Lying to a friend is wrong in general, but may be morally acceptable if it is intended to protect their life. We present ClarifyDelphi, an interactive system that learns to ask cla…

Cited by 34SourcePDFScholar
2023

Faith and Fate: Limits of Transformers on Compositionality

NeurIPS 2023spotlight

Transformer large language models (LLMs) have sparked admiration for their exceptional performance on tasks that demand intricate multi-step reasoning. Yet, these models simultaneously show failures on surprisingly trivial problems. This begs the question: Are these errors incidental, or do they si…

2023

Fusing Pre-Trained Language Models With Multimodal Prompts Through Reinforcement Learning

CVPR 2023poster

Language models are capable of commonsense reasoning: while domain-specific models can learn from explicit knowledge (e.g. commonsense graphs [6], ethical norms [25]), and larger models like GPT-3 manifest broad commonsense reasoning capacity. Can their knowledge be extended to multimodal inputs suc…

2023

Generating Sequences by Learning to Self-Correct

ICLR 2023poster

Sequence generation applications require satisfying semantic constraints, such as ensuring that programs are correct, using certain keywords, or avoiding undesirable content. Language models, whether fine-tuned or prompted with few-shot demonstrations, frequently violate these constraints, and lack…

Cited by 122SourcePDFScholar
2023

I2D2: Inductive Knowledge Distillation with NeuroLogic and Self-Imitation

ACL 2023long

Commonsense capabilities of pre-trained language models dramatically improve with scale, leading many to believe that scale is the only winning recipe. But is it? Here, we investigate an alternative that a priori seems impossible: can smaller language models (e.g., GPT-2) win over models that are or…

Cited by 32SourcePDFScholar
2023

Inference-Time Policy Adapters (IPA): Tailoring Extreme-Scale LMs without Fine-tuning

EMNLP 2023long main

While extreme-scale language models have demonstrated exceptional performance on a variety of language tasks, the degree of control over these language models through pure prompting can often be limited. Directly fine-tuning such language models can be effective for tailoring them, but it can be eit…

Cited by 0SourcecodeScholar
2023

Localized Symbolic Knowledge Distillation for Visual Commonsense Models

NeurIPS 2023poster

Instruction following vision-language (VL) models offer a flexible interface that supports a broad range of multimodal tasks in a zero-shot fashion. However, interfaces that operate on full images do not directly enable the user to “point to" and access specific regions within images. This capabilit…

Cited by 13SourcePDFScholar
2023

NovaCOMET: Open Commonsense Foundation Models with Symbolic Knowledge Distillation

EMNLP 2023long findings

We present NovaCOMET, an open commonsense knowledge model, that combines the best aspects of knowledge and general task models. Compared to previous knowledge models, NovaCOMET allows open-format relations enabling direct application to reasoning tasks; compared to general task models like Flan-T5,…

Cited by 0SourceScholar
2023

SODA: Million-scale Dialogue Distillation with Social Commonsense Contextualization

EMNLP 2023long main

Data scarcity has been a long standing issue in the field of open-domain social dialogue. To quench this thirst, we present SODA: the first publicly available, million-scale high-quality social dialogue dataset. By contextualizing social commonsense knowledge from a knowledge graph, we are able to d…

Cited by 0SourcecodeScholar
2023

STEER: Unified Style Transfer with Expert Reinforcement

EMNLP 2023long findings

While text style transfer has many applications across natural language processing, the core premise of transferring from a single source style is unrealistic in a real-world setting. In this work, we focus on arbitrary style transfer: rewriting a text from an arbitrary, unknown style to a target st…

Cited by 0SourcecodeScholar
2022

Connecting the Dots between Audio and Text without Parallel Data through Visual Knowledge Transfer

NAACL 2022long

Machines that can represent and describe environmental soundscapes have practical potential, e.g., for audio tagging and captioning. Prevailing learning paradigms of audio-text connections have been relying on parallel audio-text data, which is, however, scarcely available on the web. We propose VIP…

2022

Generated Knowledge Prompting for Commonsense Reasoning

ACL 2022long

It remains an open question whether incorporating external knowledge benefits commonsense reasoning while maintaining the flexibility of pretrained sequence models. To investigate this question, we develop generated knowledge prompting, which consists of generating knowledge from a language model, t…

2022

MERLOT Reserve: Neural Script Knowledge Through Vision and Language and Sound

CVPR 2022oral

As humans, we navigate a multimodal world, building a holistic understanding from all our senses. We introduce MERLOT Reserve, a model that represents videos jointly over time -- through a new training objective that learns from audio, subtitles, and video frames. Given a video, we replace snippets…

Cited by 286PDFScholar
2022

NaturalProver: Grounded Mathematical Proof Generation with Language Models

NeurIPS 2022accept

Theorem proving in natural mathematical language – the mixture of symbolic and natural language used by humans – plays a central role in mathematical advances and education, and tests aspects of reasoning that are core to intelligence. Yet it has remained underexplored with modern generative models.…

2022

NeuroLogic A*esque Decoding: Constrained Text Generation with Lookahead Heuristics

NAACL 2022long

The dominant paradigm for neural text generation is left-to-right decoding from autoregressive language models. Constrained or controllable generation under complex lexical constraints, however, requires foresight to plan ahead feasible future paths. Drawing inspiration from the A* search algorithm,…

2022

ProsocialDialog: A Prosocial Backbone for Conversational Agents

EMNLP 2022main

Most existing dialogue systems fail to respond properly to potentially unsafe user utterances by either ignoring or passively agreeing with them. To address this issue, we introduce ProsocialDialog, the first large-scale multi-turn dialogue dataset to teach conversational agents to respond to proble…

2022

QUARK: Controllable Text Generation with Reinforced Unlearning

NeurIPS 2022accept

Large-scale language models often learn behaviors that are misaligned with user expectations. Generated text may contain offensive or toxic language, contain significant repetition, or be of a different sentiment than desired by the user. We consider the task of unlearning these misalignments by fin…

2022

Rainier: Reinforced Knowledge Introspector for Commonsense Question Answering

EMNLP 2022main

Knowledge underpins reasoning. Recent research demonstrates that when relevant knowledge is provided as additional context to commonsense question answering (QA), it can substantially enhance the performance even on top of state-of-the-art. The fundamental challenge is where and how to find such kno…

2022

Symbolic Knowledge Distillation: from General Language Models to Commonsense Models

NAACL 2022long

The common practice for training commonsense models has gone from–human–to–corpus–to–machine: humans author commonsense knowledge graphs in order to train commonsense models. In this work, we investigate an alternative, from–machine–to–corpus–to–machine: general language models author these commonse…

2022

Twist Decoding: Diverse Generators Guide Each Other

EMNLP 2022main

Many language generation models are now available for a wide range of generation tasks, including machine translation and summarization. Combining such diverse models may lead to further progress, but ensembling generation models is challenging during inference: conventional ensembling methods (e.g.…

2021

DExperts: Decoding-Time Controlled Text Generation with Experts and Anti-Experts

ACL 2021long

Despite recent advances in natural language generation, it remains challenging to control attributes of generated text. We propose DExperts: Decoding-time Experts, a decoding-time method for controlled text generation that combines a pretrained language model with “expert” LMs and/or “anti-expert” L…

2021

MERLOT: Multimodal Neural Script Knowledge Models

NeurIPS 2021oral

As humans, we understand events in the visual world contextually, performing multimodal reasoning across time to make inferences about the past, present, and future. We introduce MERLOT, a model that learns multimodal script knowledge by watching millions of YouTube videos with transcribed speech --…

Cited by 423SourcePDFScholar
2021

NeuroLogic Decoding: (Un)supervised Neural Text Generation with Predicate Logic Constraints

NAACL 2021long

Conditional text generation often requires lexical constraints, i.e., which words should or shouldn’t be included in the output text. While the dominant recipe for conditional text generation has been large-scale pretrained language models that are finetuned on the task-specific training data, such…

Cited by 165SourcePDFScholar
2021

Reflective Decoding: Beyond Unidirectional Generation with Off-the-Shelf Language Models

ACL 2021long

Publicly available, large pretrained Language Models (LMs) generate text with remarkable quality, but only sequentially from left to right. As a result, they are not immediately applicable to generation tasks that break the unidirectional assumption, such as paraphrasing or text-infilling, necessita…