Synthetic Data for any Differentiable Target

Fuente: arXiv
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Main Authors: Thrush, Tristan, Park, Sung Min, Brunborg, Herman, Bailey, Luke, Roed, Marcel, Band, Neil, Potts, Christopher, Hashimoto, Tatsunori
Format: Preprint
Published: 2026
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author Thrush, Tristan
Park, Sung Min
Brunborg, Herman
Bailey, Luke
Roed, Marcel
Band, Neil
Potts, Christopher
Hashimoto, Tatsunori
author_facet Thrush, Tristan
Park, Sung Min
Brunborg, Herman
Bailey, Luke
Roed, Marcel
Band, Neil
Potts, Christopher
Hashimoto, Tatsunori
contents What are the limits of controlling language models via synthetic training data? We develop a reinforcement learning (RL) primitive, the Dataset Policy Gradient (DPG), which can precisely optimize synthetic data generators to produce a dataset of targeted examples. When used for supervised fine-tuning (SFT) of a target model, these examples cause the target model to do well on a differentiable metric of our choice. Our approach achieves this by taking exact data attribution via higher-order gradients and using those scores as policy gradient rewards. We prove that this procedure closely approximates the true, intractable gradient for the synthetic data generator. To illustrate the potential of DPG, we show that, using only SFT on generated examples, we can cause the target model's LM head weights to (1) embed a QR code, (2) embed the pattern $\texttt{67}$, and (3) have lower $\ell^2$ norm. We additionally show that we can cause the generator to (4) rephrase inputs in a new language and (5) produce a specific UUID, even though neither of these objectives is conveyed in the generator's input prompts. These findings suggest that DPG is a powerful and flexible technique for shaping model properties using only synthetic training examples.
format Preprint
id arxiv_https___arxiv_org_abs_2604_08423
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Synthetic Data for any Differentiable Target
Thrush, Tristan
Park, Sung Min
Brunborg, Herman
Bailey, Luke
Roed, Marcel
Band, Neil
Potts, Christopher
Hashimoto, Tatsunori
Computation and Language
Artificial Intelligence
Machine Learning
What are the limits of controlling language models via synthetic training data? We develop a reinforcement learning (RL) primitive, the Dataset Policy Gradient (DPG), which can precisely optimize synthetic data generators to produce a dataset of targeted examples. When used for supervised fine-tuning (SFT) of a target model, these examples cause the target model to do well on a differentiable metric of our choice. Our approach achieves this by taking exact data attribution via higher-order gradients and using those scores as policy gradient rewards. We prove that this procedure closely approximates the true, intractable gradient for the synthetic data generator. To illustrate the potential of DPG, we show that, using only SFT on generated examples, we can cause the target model's LM head weights to (1) embed a QR code, (2) embed the pattern $\texttt{67}$, and (3) have lower $\ell^2$ norm. We additionally show that we can cause the generator to (4) rephrase inputs in a new language and (5) produce a specific UUID, even though neither of these objectives is conveyed in the generator's input prompts. These findings suggest that DPG is a powerful and flexible technique for shaping model properties using only synthetic training examples.
title Synthetic Data for any Differentiable Target
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2604.08423