Delta激活:微调大型语言模型的一种表征方法
Delta Activations: A Representation for Finetuned Large Language Models
September 4, 2025
作者: Zhiqiu Xu, Amish Sethi, Mayur Naik, Ser-Nam Lim
cs.AI
摘要
开源大型语言模型(LLMs)的成功,使得社区能够创建大量针对特定任务和领域进行后训练的模型。然而,由于元数据的不一致和存储库的非结构化,浏览和理解这些模型仍然具有挑战性。我们提出了Delta Activations方法,通过测量微调模型相对于基础模型内部激活的变化,将其表示为向量嵌入。这种表示方法能够有效地按领域和任务进行聚类,揭示模型生态中的结构。Delta Activations还展现出一些理想特性:它在不同的微调设置下表现出鲁棒性,并在微调数据集混合时展现出可加性。此外,我们展示了Delta Activations能够通过少样本微调嵌入任务,并进一步探索了其在模型选择和合并中的应用。我们希望Delta Activations能够促进公开可用模型的复用实践。代码可在https://github.com/OscarXZQ/delta_activations获取。
English
The success of powerful open source Large Language Models (LLMs) has enabled
the community to create a vast collection of post-trained models adapted to
specific tasks and domains. However, navigating and understanding these models
remains challenging due to inconsistent metadata and unstructured repositories.
We introduce Delta Activations, a method to represent finetuned models as
vector embeddings by measuring shifts in their internal activations relative to
a base model. This representation allows for effective clustering by domain and
task, revealing structure in the model landscape. Delta Activations also
demonstrate desirable properties: it is robust across finetuning settings and
exhibits an additive property when finetuning datasets are mixed. In addition,
we show that Delta Activations can embed tasks via few-shot finetuning, and
further explore its use for model selection and merging. We hope Delta
Activations can facilitate the practice of reusing publicly available models.
Code is available at https://github.com/OscarXZQ/delta_activations.