@inproceedings{zhang-etal-2026-llm-fine,
title = "{LLM} Fine-tuning with an Unconstrained Fine-tuned Teacher",
author = "Zhang, Jianhao and
Wu, Ou and
Du, Yi",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.1310/",
pages = "29812--29839",
ISBN = "979-8-89176-459-0",
abstract = "Fine-tuning large language models (LLMs) on a single target task requires balancing task adaptation with retention of prior capabilities. Existing teachers mainly guide preservation or transfer, but do not identify which target-task samples should be emphasized when fine-tuning must retain prior capabilities. We propose the **U**nconstrained **F**ine-tuned **T**eacher (**UFT**), shifting the teacher role from ``knowledge transfer'' to ``value discovery''. UFT is obtained by unconstrained fine-tuning on the target task and then compared with the source model to identify high-value samples. These samples are upweighted during student fine-tuning and receive value-weighted UFT-guided distillation, allowing the student to prioritize task-critical signals while preserving prior capabilities. Experiments on Magicoder and MetaMathQA show that UFT improves the trade-off between target-task performance and prior-capability retention, while converging faster and more stably. By turning teacher behavior into sample-value discovery, UFT establishes a new teacher role for data-efficient fine-tuning."
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<abstract>Fine-tuning large language models (LLMs) on a single target task requires balancing task adaptation with retention of prior capabilities. Existing teachers mainly guide preservation or transfer, but do not identify which target-task samples should be emphasized when fine-tuning must retain prior capabilities. We propose the **U**nconstrained **F**ine-tuned **T**eacher (**UFT**), shifting the teacher role from “knowledge transfer” to “value discovery”. UFT is obtained by unconstrained fine-tuning on the target task and then compared with the source model to identify high-value samples. These samples are upweighted during student fine-tuning and receive value-weighted UFT-guided distillation, allowing the student to prioritize task-critical signals while preserving prior capabilities. Experiments on Magicoder and MetaMathQA show that UFT improves the trade-off between target-task performance and prior-capability retention, while converging faster and more stably. By turning teacher behavior into sample-value discovery, UFT establishes a new teacher role for data-efficient fine-tuning.</abstract>
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%0 Conference Proceedings
%T LLM Fine-tuning with an Unconstrained Fine-tuned Teacher
%A Zhang, Jianhao
%A Wu, Ou
%A Du, Yi
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F zhang-etal-2026-llm-fine
%X Fine-tuning large language models (LLMs) on a single target task requires balancing task adaptation with retention of prior capabilities. Existing teachers mainly guide preservation or transfer, but do not identify which target-task samples should be emphasized when fine-tuning must retain prior capabilities. We propose the **U**nconstrained **F**ine-tuned **T**eacher (**UFT**), shifting the teacher role from “knowledge transfer” to “value discovery”. UFT is obtained by unconstrained fine-tuning on the target task and then compared with the source model to identify high-value samples. These samples are upweighted during student fine-tuning and receive value-weighted UFT-guided distillation, allowing the student to prioritize task-critical signals while preserving prior capabilities. Experiments on Magicoder and MetaMathQA show that UFT improves the trade-off between target-task performance and prior-capability retention, while converging faster and more stably. By turning teacher behavior into sample-value discovery, UFT establishes a new teacher role for data-efficient fine-tuning.
%U https://aclanthology.org/2026.emnlp-main.1310/
%P 29812-29839
Markdown (Informal)
[LLM Fine-tuning with an Unconstrained Fine-tuned Teacher](https://aclanthology.org/2026.emnlp-main.1310/) (Zhang et al., EMNLP 2026)
ACL