Bi-level Unbalanced Optimal Transport for Partial Domain Adaptation

TL;DR

This paper introduces a bi-level unbalanced optimal transport model for partial domain adaptation, effectively aligning cross-domain samples while identifying outlier classes through a unified framework that captures sample and class relations.

Contribution

The novel BUOT model simultaneously models sample-wise and class-wise relations, improving outlier detection and alignment in partial domain adaptation.

Findings

Outperforms existing methods on benchmark datasets.

Effectively distinguishes outlier classes during domain adaptation.

Provides a fast and efficient computation method.

Abstract

Partial domain adaptation (PDA) problem requires aligning cross-domain samples while distinguishing the outlier classes for accurate knowledge transfer. The widely used weighting framework tries to address the outlier classes by introducing the reweighed source domain with a similar label distribution to the target domain. However, the empirical modeling of weights can only characterize the sample-wise relations, which leads to insufficient exploration of cluster structures, and the weights could be sensitive to the inaccurate prediction and cause confusion on the outlier classes. To tackle these issues, we propose a Bi-level Unbalanced Optimal Transport (BUOT) model to simultaneously characterize the sample-wise and class-wise relations in a unified transport framework. Specifically, a cooperation mechanism between sample-level and class-level transport is introduced, where the sample-level transport provides essential structure information for the class-level knowledge transfer, while the class-level transport supplies discriminative information for the outlier identification. The bi-level transport plan provides guidance for the alignment process. By incorporating the label-aware transport cost, the local transport structure is ensured and a fast computation formulation is derived to improve the efficiency. Extensive experiments on benchmark datasets validate the competitiveness of BUOT.