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Nathan Grinsztajn

8 accepted papers

2025

Memory-Enhanced Neural Solvers for Routing Problems

NeurIPS 2025spotlight

Routing Problems are central to many real-world applications, yet remain challenging due to their (NP-)hard nature. Amongst existing approaches, heuristics often offer the best trade-off between quality and scalability, making them suitable for industrial use. While Reinforcement Learning (RL) offer…

Cited by 0SourceScholar
2025

ShiQ: Bringing back Bellman to LLMs

NeurIPS 2025poster

The fine-tuning of pre-trained large language models (LLMs) using reinforcement learning (RL) is generally formulated as direct policy optimization. This approach was naturally favored as it efficiently improves a pretrained LLM with simple gradient updates. Another RL paradigm, Q-learning methods,…

Cited by 3SourceScholar
2024

Contrastive Policy Gradient: Aligning LLMs on sequence-level scores in a supervised-friendly fashion

EMNLP 2024main

Reinforcement Learning (RL) has been used to finetune Large Language Models (LLMs) using a reward model trained from preference data, to better align with human judgment. The recently introduced direct alignment methods, which are often simpler, more stable, and computationally lighter, can more dir…

Cited by 3SourcePDFScholar
2024

Jumanji: a Diverse Suite of Scalable Reinforcement Learning Environments in JAX

ICLR 2024poster

Open-source reinforcement learning (RL) environments have played a crucial role in driving progress in the development of AI algorithms. In modern RL research, there is a need for simulated environments that are performant, scalable, and modular to enable their utilization in a wider range of potent…

2024

Should we be going MAD? A Look at Multi-Agent Debate Strategies for LLMs

ICML 2024poster

Recent advancements in large language models (LLMs) underscore their potential for responding to inquiries in various domains. However, ensuring that generative agents provide accurate and reliable answers remains an ongoing challenge. In this context, multi-agent debate (MAD) has emerged as a promi…

2023

Combinatorial Optimization with Policy Adaptation using Latent Space Search

NeurIPS 2023poster

Combinatorial Optimization underpins many real-world applications and yet, designing performant algorithms to solve these complex, typically NP-hard, problems remains a significant research challenge. Reinforcement Learning (RL) provides a versatile framework for designing heuristics across a broad…

2023

Winner Takes It All: Training Performant RL Populations for Combinatorial Optimization

NeurIPS 2023poster

Applying reinforcement learning (RL) to combinatorial optimization problems is attractive as it removes the need for expert knowledge or pre-solved instances. However, it is unrealistic to expect an agent to solve these (often NP-)hard problems in a single shot at inference due to their inherent com…

Cited by 36SourcePDFScholar
2021

There Is No Turning Back: A Self-Supervised Approach for Reversibility-Aware Reinforcement Learning

NeurIPS 2021poster

We propose to learn to distinguish reversible from irreversible actions for better informed decision-making in Reinforcement Learning (RL). From theoretical considerations, we show that approximate reversibility can be learned through a simple surrogate task: ranking randomly sampled trajectory even…

Cited by 24SourcePDFScholar