On the Emergence of Cross-Task Linearity in the Pretraining-Finetuning Paradigm

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Hauptverfasser: Zhou, Zhanpeng, Chen, Zijun, Chen, Yilan, Zhang, Bo, Yan, Junchi
Format: Preprint
Veröffentlicht: 2024
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author Zhou, Zhanpeng
Chen, Zijun
Chen, Yilan
Zhang, Bo
Yan, Junchi
author_facet Zhou, Zhanpeng
Chen, Zijun
Chen, Yilan
Zhang, Bo
Yan, Junchi
contents The pretraining-finetuning paradigm has become the prevailing trend in modern deep learning. In this work, we discover an intriguing linear phenomenon in models that are initialized from a common pretrained checkpoint and finetuned on different tasks, termed as Cross-Task Linearity (CTL). Specifically, we show that if we linearly interpolate the weights of two finetuned models, the features in the weight-interpolated model are often approximately equal to the linear interpolation of features in two finetuned models at each layer. We provide comprehensive empirical evidence supporting that CTL consistently occurs for finetuned models that start from the same pretrained checkpoint. We conjecture that in the pretraining-finetuning paradigm, neural networks approximately function as linear maps, mapping from the parameter space to the feature space. Based on this viewpoint, our study unveils novel insights into explaining model merging/editing, particularly by translating operations from the parameter space to the feature space. Furthermore, we delve deeper into the root cause for the emergence of CTL, highlighting the role of pretraining.
format Preprint
id arxiv_https___arxiv_org_abs_2402_03660
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Emergence of Cross-Task Linearity in the Pretraining-Finetuning Paradigm
Zhou, Zhanpeng
Chen, Zijun
Chen, Yilan
Zhang, Bo
Yan, Junchi
Machine Learning
Artificial Intelligence
The pretraining-finetuning paradigm has become the prevailing trend in modern deep learning. In this work, we discover an intriguing linear phenomenon in models that are initialized from a common pretrained checkpoint and finetuned on different tasks, termed as Cross-Task Linearity (CTL). Specifically, we show that if we linearly interpolate the weights of two finetuned models, the features in the weight-interpolated model are often approximately equal to the linear interpolation of features in two finetuned models at each layer. We provide comprehensive empirical evidence supporting that CTL consistently occurs for finetuned models that start from the same pretrained checkpoint. We conjecture that in the pretraining-finetuning paradigm, neural networks approximately function as linear maps, mapping from the parameter space to the feature space. Based on this viewpoint, our study unveils novel insights into explaining model merging/editing, particularly by translating operations from the parameter space to the feature space. Furthermore, we delve deeper into the root cause for the emergence of CTL, highlighting the role of pretraining.
title On the Emergence of Cross-Task Linearity in the Pretraining-Finetuning Paradigm
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2402.03660