Autoregressive Language Models are Secretly Energy-Based Models: Insights into the Lookahead Capabilities of Next-Token Prediction

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Main Authors: Blondel, Mathieu, Sander, Michael E., Vivier-Ardisson, Germain, Liu, Tianlin, Roulet, Vincent
Format: Preprint
Published: 2025
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author Blondel, Mathieu
Sander, Michael E.
Vivier-Ardisson, Germain
Liu, Tianlin
Roulet, Vincent
author_facet Blondel, Mathieu
Sander, Michael E.
Vivier-Ardisson, Germain
Liu, Tianlin
Roulet, Vincent
contents Autoregressive models (ARMs) currently constitute the dominant paradigm for large language models (LLMs). Energy-based models (EBMs) represent another class of models, which have historically been less prevalent in LLM development, yet naturally characterize the optimal policy in post-training alignment. In this paper, we provide a unified view of these two model classes. Taking the chain rule of probability as a starting point, we establish an explicit bijection between ARMs and EBMs in function space, which we show to correspond to a special case of the soft Bellman equation in maximum entropy reinforcement learning. Building upon this bijection, we derive the equivalence between supervised learning of ARMs and EBMs. Furthermore, we analyze the distillation of EBMs into ARMs by providing theoretical error bounds. Our results provide insights into the ability of ARMs to plan ahead, despite being based on the next-token prediction paradigm.
format Preprint
id arxiv_https___arxiv_org_abs_2512_15605
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Autoregressive Language Models are Secretly Energy-Based Models: Insights into the Lookahead Capabilities of Next-Token Prediction
Blondel, Mathieu
Sander, Michael E.
Vivier-Ardisson, Germain
Liu, Tianlin
Roulet, Vincent
Machine Learning
Autoregressive models (ARMs) currently constitute the dominant paradigm for large language models (LLMs). Energy-based models (EBMs) represent another class of models, which have historically been less prevalent in LLM development, yet naturally characterize the optimal policy in post-training alignment. In this paper, we provide a unified view of these two model classes. Taking the chain rule of probability as a starting point, we establish an explicit bijection between ARMs and EBMs in function space, which we show to correspond to a special case of the soft Bellman equation in maximum entropy reinforcement learning. Building upon this bijection, we derive the equivalence between supervised learning of ARMs and EBMs. Furthermore, we analyze the distillation of EBMs into ARMs by providing theoretical error bounds. Our results provide insights into the ability of ARMs to plan ahead, despite being based on the next-token prediction paradigm.
title Autoregressive Language Models are Secretly Energy-Based Models: Insights into the Lookahead Capabilities of Next-Token Prediction
topic Machine Learning
url https://arxiv.org/abs/2512.15605