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Fahim Tajwar

10 accepted papers

2026

Accelerating Diffusion Planners in Offline RL via Reward-Aware Consistency Trajectory Distillation

ICLR 2026poster

Although diffusion models have achieved strong results in decision-making tasks, their slow inference speed remains a key limitation. While consistency models offer a potential solution, existing applications to decision-making either struggle with suboptimal demonstrations under behavior cloning or…

Cited by 0SourceScholar
2026

Beyond Scalar Rewards: Learning from Text Feedback in LLM Post-Training

ICML 2026poster

The success of RL for LLM post-training stems from an unreasonably uninformative source: a single bit of information per rollout as binary reward or preference label. At the other extreme, distillation offers dense supervision but requires demonstrations, which are costly and difficult to scale. We …

Cited by 0SourceScholar
2026

Maximum Likelihood Reinforcement Learning

ICML 2026oral

Maximum likelihood is fundamental to supervised learning but it cannot be directly applied in correctness-based problems with non-differentiable sampling. In these settings, reinforcement learning (RL) is typically used to maximize expected reward. We show that for binary correctness tasks, expected…

Cited by 0SourceScholar
2025

Retrospective In-Context Learning for Temporal Credit Assignment with Large Language Models

NeurIPS 2025poster

Learning from self-sampled data and sparse environmental feedback remains a fundamental challenge in training self-evolving agents. Temporal credit assignment mitigates this issue by transforming sparse feedback into dense supervision signals. However, previous approaches typically depend on domain-…

Cited by 0SourceScholar
2025

Training a Generally Curious Agent

ICML 2025oral

Efficient exploration is essential for intelligent systems interacting with their environment, but existing language models often fall short in scenarios that require strategic information gathering. In this paper, we present **Paprika**, a fine-tuning approach that enables language models to develo…

2024

Preference Fine-Tuning of LLMs Should Leverage Suboptimal, On-Policy Data

ICML 2024poster

Learning from preference labels plays a crucial role in fine-tuning large language models --- this is done via supervised learning, on-policy reinforcement learning (RL), or contrastive learning. Different methods come with different implementation tradeoffs, and existing empirical findings present…

2023

Surgical Fine-Tuning Improves Adaptation to Distribution Shifts

ICLR 2023poster

A common approach to transfer learning under distribution shift is to fine-tune the last few layers of a pre-trained model, preserving learned features while also adapting to the new task. This paper shows that in such settings, selectively fine-tuning a subset of layers (which we term surgical fine…

2022

Do deep networks transfer invariances across classes?

ICLR 2022poster

In order to generalize well, classifiers must learn to be invariant to nuisance transformations that do not alter an input's class. Many problems have "class-agnostic" nuisance transformations that apply similarly to all classes, such as lighting and background changes for image classification. Neur…

2022

When to Ask for Help: Proactive Interventions in Autonomous Reinforcement Learning

NeurIPS 2022accept

A long-term goal of reinforcement learning is to design agents that can autonomously interact and learn in the world. A critical challenge to such autonomy is the presence of irreversible states which require external assistance to recover from, such as when a robot arm has pushed an object off of a…