概述
It matters because it can improve reasoning on tasks where a correct answer is easy to check but hard to demonstrate step by step. Its main risk is reward hacking, where the model learns to please the grader instead of solving the task.
深入探討
Standard supervised fine-tuning shows the model an input and the exact output you want, and trains it to imitate. That works when you can write good target outputs, but it teaches the surface form of answers rather than the process of reaching them. Reinforcement fine-tuning works differently. For each training prompt, the model samples one or more candidate answers. A grader assigns each a score, often between 0 and 1. The training algorithm then adjusts the model so that answers scoring above average become more likely and those below average less likely. Over many rounds, the model keeps the reasoning patterns that earn reward. Graders come in a few kinds. Exact or string-match graders check whether a final answer equals a reference. Programmatic graders run code, such as unit tests or a numerical tolerance check. Model-based graders use another language model with a rubric to judge qualities that are hard to check mechanically. Graders can also give partial credit, which gives the model a smoother signal. RFT suits tasks with verifiable or reliably gradable answers where experts agree on what is correct: classification with defined labels, maths, code, structured extraction, and some specialised judgement tasks. It is a poor fit where quality is subjective and graders disagree. OpenAI previewed a reinforcement fine-tuning service in December 2024, and reasoning models more broadly have been trained with reinforcement learning on verifiable rewards. The central failure mode is reward hacking. The model optimises the grader, not your intent. If a grader only checks the final line, the model may produce a correct-looking final line with broken reasoning. If a model grader likes length or confident wording, outputs drift toward those traits. A common misconception is that a higher training reward means a better model; it only means a better score from that grader.
戰略影響
成本與預算
多年來，架構決策決定著效能和營運成本。
更明確的決策
技術教育幫助團隊選擇正確的堆疊，而不僅僅是最新的堆疊。
品質管控
更好的工程選擇可以減少生產中的可靠性事故。
The Future of Reinforcement Fine-Tuning with Graders
Reinforcement learning on gradable tasks has become an important part of how reasoning models are trained, and hosted services are making RFT available to smaller teams. Progress is likely to depend less on the training algorithm and more on grader quality, since a model can only become as good as the signal it is optimised against. Research into more robust graders, multiple independent graders and better detection of reward hacking is active. For most organisations, the practical question will remain whether they can define correctness clearly enough to grade it.
現實世界的實施
A tax software team trains a model to classify expense items into the correct category code, with a grader that checks the predicted code against a labelled answer.
A company building a coding assistant rewards generated functions by running them against unit tests, so the reward reflects whether the code actually works.
A medical research group trains a model to rank likely genes given a list of symptoms, with a grader that gives partial credit when the correct gene appears near the top of the ranking.
A team uses a model-based grader to score customer email replies for accuracy and tone, then discovers the policy has learned to add flattering phrases the grader over-rewards.
風險與防護欄
優化一項基準測試可以隱藏更廣泛的系統弱點。
基礎設施和維護成本常常被低估。
隨著系統變得更加複雜，安全性和可觀察性差距可能會擴大。
實施路線圖
在實施之前定義延遲、品質和成本目標。
在實際負載和資料條件下進行基準測試。
儀器監控錯誤、漂移和使用者影響。
在擴展之前準備回滾和事件回應路徑。
不斷探索
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常見問題
What is Reinforcement Fine-Tuning with Graders?
Reinforcement fine-tuning (RFT) trains a model by having it generate answers, scoring those answers with a grader, and updating the model to make high-scoring answers more likely, rather than teaching it to copy example outputs. It matters because it can improve reasoning on tasks where a correct answer is easy to check but hard to demonstrate step by step. Its main risk is reward hacking, where the model learns to please the grader instead of solving the task.
How does reinforcement fine-tuning differ from supervised fine-tuning?
Supervised fine-tuning imitates targets; RFT samples answers, scores them with a grader and reinforces high-scoring ones.
Which grader type would you use to check that generated code actually works?
Programmatic graders can execute code against tests, directly measuring whether it works.
Which task is the poorest fit for RFT according to the guide?
RFT needs a reliable grade. When experts disagree about what is correct, the reward signal is noisy.
In Reinforcement Fine-Tuning with Graders: what is reward hacking?
Reward hacking happens when optimisation exploits weaknesses in the grader, raising scores without improving true quality.
Why do prompts where every sample gets the same score provide little learning signal in group-relative methods like GRPO?
GRPO uses relative scores within a group as the advantage. If all scores match, there is no difference to learn from.
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