Rethinking the Flow-Based Gradual Domain Adaption: A Semi-Dual Optimal Transport Perspective

Fuente: arXiv
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Auteurs principaux: Chen, Zhichao, Zhuang, Zhan, Teng, Yunfei, Wang, Hao, Wang, Fangyikang, Li, Zhengnan, Liu, Tianqiao, Li, Haoxuan, Lin, Zhouchen
Format: Preprint
Publié: 2026
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author Chen, Zhichao
Zhuang, Zhan
Teng, Yunfei
Wang, Hao
Wang, Fangyikang
Li, Zhengnan
Liu, Tianqiao
Li, Haoxuan
Lin, Zhouchen
author_facet Chen, Zhichao
Zhuang, Zhan
Teng, Yunfei
Wang, Hao
Wang, Fangyikang
Li, Zhengnan
Liu, Tianqiao
Li, Haoxuan
Lin, Zhouchen
contents Gradual domain adaptation (GDA) aims to mitigate domain shift by progressively adapting models from the source domain to the target domain via intermediate domains. However, real intermediate domains are often unavailable or ineffective, necessitating the synthesis of intermediate samples. Flow-based models have recently been used for this purpose by interpolating between source and target distributions; however, their training typically relies on sample-based log-likelihood estimation, which can discard useful information and thus degrade GDA performance. The key to addressing this limitation is constructing the intermediate domains via samples directly. To this end, we propose an Entropy-regularized Semi-dual Unbalanced Optimal Transport (E-SUOT) framework to construct intermediate domains. Specifically, we reformulate flow-based GDA as a Lagrangian dual problem and derive an equivalent semi-dual objective that circumvents the need for likelihood estimation. However, the dual problem leads to an unstable min-max training procedure. To alleviate this issue, we further introduce entropy regularization to convert it into a more stable alternative optimization procedure. Based on this, we propose a novel GDA training framework and provide theoretical analysis in terms of stability and generalization. Finally, extensive experiments are conducted to demonstrate the efficacy of the E-SUOT framework.
format Preprint
id arxiv_https___arxiv_org_abs_2602_01179
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Rethinking the Flow-Based Gradual Domain Adaption: A Semi-Dual Optimal Transport Perspective
Chen, Zhichao
Zhuang, Zhan
Teng, Yunfei
Wang, Hao
Wang, Fangyikang
Li, Zhengnan
Liu, Tianqiao
Li, Haoxuan
Lin, Zhouchen
Machine Learning
Gradual domain adaptation (GDA) aims to mitigate domain shift by progressively adapting models from the source domain to the target domain via intermediate domains. However, real intermediate domains are often unavailable or ineffective, necessitating the synthesis of intermediate samples. Flow-based models have recently been used for this purpose by interpolating between source and target distributions; however, their training typically relies on sample-based log-likelihood estimation, which can discard useful information and thus degrade GDA performance. The key to addressing this limitation is constructing the intermediate domains via samples directly. To this end, we propose an Entropy-regularized Semi-dual Unbalanced Optimal Transport (E-SUOT) framework to construct intermediate domains. Specifically, we reformulate flow-based GDA as a Lagrangian dual problem and derive an equivalent semi-dual objective that circumvents the need for likelihood estimation. However, the dual problem leads to an unstable min-max training procedure. To alleviate this issue, we further introduce entropy regularization to convert it into a more stable alternative optimization procedure. Based on this, we propose a novel GDA training framework and provide theoretical analysis in terms of stability and generalization. Finally, extensive experiments are conducted to demonstrate the efficacy of the E-SUOT framework.
title Rethinking the Flow-Based Gradual Domain Adaption: A Semi-Dual Optimal Transport Perspective
topic Machine Learning
url https://arxiv.org/abs/2602.01179