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Hongyuan Mei

24 accepted papers

2026

$\nabla$-Reasoner: LLM Reasoning via Test-Time Gradient Descent in Textual Space

ICLR 2026poster

Scaling inference-time compute for Large Language Models (LLMs) has unlocked unprecedented reasoning capabilities. However, existing inference-time scaling methods typically rely on inefficient and suboptimal discrete search algorithms or trial-and-error prompting to improve the online policy. In th…

Cited by 0SourcecodeScholar
2026

FlowRL: Matching Reward Distributions for LLM Reasoning

ICLR 2026poster

We propose FlowRL: matching the full reward distribution via flow balancing instead of solely maximizing rewards in large language model (LLM) reinforcement learning (RL). Recent advanced reasoning models adopt reward-maximizing methods (e.g., PPO and GRPO), which tend to over-optimize dominant rewa…

Cited by 0SourcecodeScholar
2026

Generalization of RLVR Using Causal Reasoning as a Testbed

ICLR 2026poster

Reinforcement learning with verifiable rewards (RLVR) has emerged as a promising paradigm for post-training large language models (LLMs) on complex reasoning tasks. Yet, the conditions under which RLVR yields robust generalization remain poorly understood. This paper provides an empirical study of R…

Cited by 0SourceScholar
2026

LLMs Must Think Thrice to Solve Executable Counterfactuals

ICLR 2026poster

Counterfactual reasoning, a hallmark of intelligence, consists of three steps: inferring latent variables from observations (abduction), constructing alternative situations (interventions), and predicting the outcomes of the alternatives (prediction). This skill is essential for advancing LLMs' caus…

Cited by 0SourceScholar
2026

MEMO: Memory-Augmented Model Context Optimization for Robust Multi-Turn Multi-Agent LLM Games

ICML 2026poster

Multi-turn, multi-agent LLM game evaluations often exhibit substantial run-to-run variance. In long-horizon interactions, small early deviations compound across turns and are amplified by multi-agent coupling, biasing win rate estimates and destabilizing comparative rankings across repeated tourname…

Cited by 0SourcecodeScholar
2025

CaseSumm: A Large-Scale Dataset for Long-Context Summarization from U.S. Supreme Court Opinions

NAACL 2025findings

This paper introduces CaseSumm, a novel dataset for long-context summarization in the legal domain that addresses the need for longer and more complex datasets for summarization evaluation. We collect 25.6K U.S. Supreme Court (SCOTUS) opinions and their official summaries, known as “syllabuses.” Our…

Cited by 0SourcePDFScholar
2025

Creativity or Brute Force? Using Brainteasers as a Window into the Problem-Solving Abilities of Large Language Models

NeurIPS 2025poster

Accuracy remains a standard metric for evaluating AI systems, but it offers limited insight into how models arrive at their solutions. In this work, we introduce a benchmark based on brainteasers written in long narrative form to probe more deeply into the types of reasoning strategies that models…

Cited by 0SourceScholar
2024

EasyTPP: Towards Open Benchmarking Temporal Point Processes

ICLR 2024poster

Continuous-time event sequences play a vital role in real-world domains such as healthcare, finance, online shopping, social networks, and so on. To model such data, temporal point processes (TPPs) have emerged as the most natural and competitive models, making a significant impact in both academic…

2024

GMP-AR: Granularity Message Passing and Adaptive Reconciliation for Temporal Hierarchy Forecasting

AAAI 2024technical

Time series forecasts of different temporal granularity are widely used in real-world applications, e.g., sales prediction in days and weeks for making different inventory plans. However, these tasks are usually solved separately without ensuring coherence, which is crucial for aligning downstream d…

Cited by 0SourcePDFScholar
2024

Statler: State-Maintaining Language Models for Embodied Reasoning

ICRA 2024poster

There has been a significant research interest in employing large language models to empower intelligent robots with complex reasoning. Existing work focuses on harnessing their abilities to reason about the histories of their actions and observations. In this paper, we explore a new dimension in wh…

Cited by 41SourcecodeScholar
2024

Transcrib3D: 3D Referring Expression Resolution through Large Language Models

IROS 2024poster

If robots are to work effectively alongside people, they must be able to interpret natural language references to objects in their 3D environment. Understanding 3D referring expressions is challenging—it requires the ability to both parse the 3D structure of the scene and correctly ground free-form…

Cited by 5SourcecodeScholar
2023

Bellman Meets Hawkes: Model-Based Reinforcement Learning via Temporal Point Processes

AAAI 2023technical

We consider a sequential decision making problem where the agent faces the environment characterized by the stochastic discrete events and seeks an optimal intervention policy such that its long-term reward is maximized. This problem exists ubiquitously in social media, finance and health informatic…

2023

Continuous-Time Decision Transformer for Healthcare Applications

AISTATS 2023poster

Offline reinforcement learning (RL) is a promising approach for training intelligent medical agents to learn treatment policies and assist decision making in many healthcare applications, such as scheduling clinical visits and assigning dosages for patients with chronic conditions. In this paper, we…

2023

Language Models Can Improve Event Prediction by Few-Shot Abductive Reasoning

NeurIPS 2023poster

Large language models have shown astonishing performance on a wide range of reasoning tasks. In this paper, we investigate whether they could reason about real-world events and help improve the prediction performance of event sequence models. We design LAMP, a framework that integrates a large langu…

Cited by 52SourcePDFScholar
2023

Robustness of Learning from Task Instructions

ACL 2023findings

Traditional supervised learning mostly works on individual tasks and requires training on a large set of task-specific examples. This paradigm seriously hinders the development of task generalization since preparing a task-specific example set is costly. To build a system that can quickly and easily…

2022

HYPRO: A Hybridly Normalized Probabilistic Model for Long-Horizon Prediction of Event Sequences

NeurIPS 2022accept

In this paper, we tackle the important yet under-investigated problem of making long-horizon prediction of event sequences. Existing state-of-the-art models do not perform well at this task due to their autoregressive structure. We propose HYPRO, a hybridly normalized probabilistic model that natura…

Cited by 38SourcePDFScholar
2022

Hidden State Variability of Pretrained Language Models Can Guide Computation Reduction for Transfer Learning

EMNLP 2022finding

While transferring a pretrained language model, common approaches conventionally attach their task-specific classifiers to the top layer and adapt all the pretrained layers. We investigate whether one could make a task-specific selection on which subset of the layers to adapt and where to place the…

2022

Tiny-Attention Adapter: Contexts Are More Important Than the Number of Parameters

EMNLP 2022main

Adapter-tuning is a paradigm that transfers a pretrained language model to downstream tasks by adding and tuning a small number of new parameters. Previously proposed adapter architectures are all feed-forward neural networks. In this paper, we investigate the effectiveness of using tiny-attention—i…

2022

Transformer Embeddings of Irregularly Spaced Events and Their Participants

ICLR 2022poster

The neural Hawkes process (Mei & Eisner, 2017) is a generative model of irregularly spaced sequences of discrete events. To handle complex domains with many event types, Mei et al. (2020a) further consider a setting in which each event in the sequence updates a deductive database of facts (via domai…

2020

Neural Datalog Through Time: Informed Temporal Modeling via Logical Specification

ICML 2020poster

Learning how to predict future events from patterns of past events is difficult when the set of possible event types is large. Training an unrestricted neural model might overfit to spurious patterns. To exploit domain-specific knowledge of how past events might affect an event’s present probability…

2017

The Neural Hawkes Process: A Neurally Self-Modulating Multivariate Point Process

NeurIPS 2017poster

Many events occur in the world. Some event types are stochastically excited or inhibited—in the sense of having their probabilities elevated or decreased—by patterns in the sequence of previous events. Discovering such patterns can help us predict which type of event will happen next and when. We mo…