Rethinking the Flow-Based Gradual Domain Adaption: A Semi-Dual Optimal Transport Perspective
This work addresses the information loss and performance degradation in progressive domain adaptation caused by reliance on sample-based log-likelihood estimation. To overcome this limitation, the authors propose an Entropy-Regularized Semi-dual Unbalanced Optimal Transport framework (E-SUOT). By constructing a sample-based intermediate domain, E-SUOT reformulates the flow-model-driven adaptation process as a Lagrangian dual problem and derives an equivalent semi-dual objective that circumvents explicit likelihood estimation. This formulation transforms the unstable minimax training paradigm into a stable alternating optimization procedure, for which the authors provide theoretical guarantees on stability and generalization. Experimental results demonstrate that the proposed framework significantly improves performance across multiple benchmarks in progressive domain adaptation.