Despite the progress made in domain adaptation, solving Unsupervised Domain Adaptation (UDA) problems with a general method under complex conditions caused by label shifts between domains remains a formidable task. In this work, we comprehensively investigate four distinct UDA settings including closed set domain adaptation, partial domain adaptation, open set domain adaptation, and universal domain adaptation, where shared common classes between source and target domains coexist alongside domain-specific private classes. The prominent challenges inherent in diverse UDA settings center around the discrimination of common/private classes and the precise measurement of domain discrepancy. To surmount these challenges effectively, we propose a novel yet effective method called Learning Instance Weighting for Unsupervised Domain Adaptation (LIWUDA), which caters to various UDA settings. Specifically, the proposed LIWUDA method constructs a weight network to assign weights to each instance based on its probability of belonging to common classes, and designs Weighted Optimal Transport (WOT) for domain alignment by leveraging instance weights. Additionally, the proposed LIWUDA method devises a Separate and Align (SA) loss to separate instances with low similarities and align instances with high similarities. To guide the learning of the weight network, Intra-domain Optimal Transport (IOT) is proposed to enforce the weights of instances in common classes to follow a uniform distribution. Through the integration of those three components, the proposed LIWUDA method demonstrates its capability to address all four UDA settings in a unified manner. Experimental evaluations conducted on three benchmark datasets substantiate the effectiveness of the proposed LIWUDA method.

针对无监督域自适应问题中由领域间标签偏移引起的复杂条件下的普遍方法，我们全面研究了四种不同的无监督域自适应设置，包括闭集域自适应、部分域自适应、开放集域自适应和通用域自适应，其中来源域和目标域之间存在共同类别和特定类别。基于共同类别的实例概率，我们提出了一种名为无监督域自适应学习实例加权（LIWUDA）的新方法，通过构建加权网络、设计权重最优传输（WOT）和小批量实例的分隔与对齐（SA）丢失来解决这些挑战。通过实验评估，验证了提出的LIWUDA方法的有效性。

基于实例加权的无监督领域自适应的统一框架