Papers › UFT: Unifying Supervised and Reinforcement Fine-Tuning

UFT: Unifying Supervised and Reinforcement Fine-Tuning

22 May 2025arXiv:2505.16984archive 2025-07-28

Mingyang Liu, Gabriele Farina, Asuman Ozdaglar

Post-training has demonstrated its importance in enhancing the reasoning capabilities of large language models (LLMs). The primary post-training methods can be categorized into supervised fine-tuning (SFT) and reinforcement fine-tuning (RFT). SFT is efficient and well-suited for small language models, but it may lead to overfitting and limit the reasoning abilities of larger models. In contrast, RFT generally yields better generalization but depends heavily on the strength of the base model. To address the limitations of SFT and RFT, we propose Unified Fine-Tuning (UFT), a novel post-training paradigm that unifies SFT and RFT into a single, integrated process. UFT enables the model to effectively explore solutions while incorporating informative supervision signals, bridging the gap between memorizing and thinking underlying existing methods. Notably, UFT outperforms both SFT and RFT in general, regardless of model sizes. Furthermore, we theoretically prove that UFT breaks RFT's inherent exponential sample complexity bottleneck, showing for the first time that unified training can exponentially accelerate convergence on long-horizon reasoning tasks.

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create_huggingface_actor liumy2010/uft/verl/utils/model.py official repository ran Apache-2.0 (permissive) · 360c671d6041ba3b · report
extract_step liumy2010/uft/verl/trainer/fsdp_sft_trainer.py official repository ran · honoured contract fingerprinted Apache-2.0 (permissive) · 216e28c040173a61 · report
is_transformers_version_in_range liumy2010/uft/verl/models/transformers/monkey_patch.py official repository ran Apache-2.0 (permissive) · 42a7954a8cfa89e0 · report
union_tensor_dict liumy2010/uft/verl/protocol.py official repository ran · fixture could not drive it Apache-2.0 (permissive) · 21331a58f93375e4 · report
unpad_dataproto liumy2010/uft/verl/protocol.py official repository ran · our draft was wrong Apache-2.0 (permissive) · 25f0ea3f460f6ce1 · report
apply_monkey_patch liumy2010/uft/verl/models/transformers/monkey_patch.py official repository unverified Apache-2.0 (permissive) · 1fb4adb621eefddc · report
get_huggingface_actor_config liumy2010/uft/verl/utils/model.py official repository unverified Apache-2.0 (permissive) · 19472d4343d0a082 · report
get_weight_loader liumy2010/uft/verl/models/weight_loader_registry.py official repository unverified Apache-2.0 (permissive) · 919cf310ad4c189a · report
squeeze liumy2010/uft/verl/utils/model.py official repository unverified Apache-2.0 (permissive) · 3b15e2ac7497c441 · report

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