FairWASP: Fast and Optimal Fair Wasserstein Pre-processing

Fuente: arXiv
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Autori principali: Xiong, Zikai, Dalmasso, Niccolò, Mishler, Alan, Potluru, Vamsi K., Balch, Tucker, Veloso, Manuela
Natura: Preprint
Pubblicazione: 2023
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author Xiong, Zikai
Dalmasso, Niccolò
Mishler, Alan
Potluru, Vamsi K.
Balch, Tucker
Veloso, Manuela
author_facet Xiong, Zikai
Dalmasso, Niccolò
Mishler, Alan
Potluru, Vamsi K.
Balch, Tucker
Veloso, Manuela
contents Recent years have seen a surge of machine learning approaches aimed at reducing disparities in model outputs across different subgroups. In many settings, training data may be used in multiple downstream applications by different users, which means it may be most effective to intervene on the training data itself. In this work, we present FairWASP, a novel pre-processing approach designed to reduce disparities in classification datasets without modifying the original data. FairWASP returns sample-level weights such that the reweighted dataset minimizes the Wasserstein distance to the original dataset while satisfying (an empirical version of) demographic parity, a popular fairness criterion. We show theoretically that integer weights are optimal, which means our method can be equivalently understood as duplicating or eliminating samples. FairWASP can therefore be used to construct datasets which can be fed into any classification method, not just methods which accept sample weights. Our work is based on reformulating the pre-processing task as a large-scale mixed-integer program (MIP), for which we propose a highly efficient algorithm based on the cutting plane method. Experiments demonstrate that our proposed optimization algorithm significantly outperforms state-of-the-art commercial solvers in solving both the MIP and its linear program relaxation. Further experiments highlight the competitive performance of FairWASP in reducing disparities while preserving accuracy in downstream classification settings.
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id arxiv_https___arxiv_org_abs_2311_00109
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle FairWASP: Fast and Optimal Fair Wasserstein Pre-processing
Xiong, Zikai
Dalmasso, Niccolò
Mishler, Alan
Potluru, Vamsi K.
Balch, Tucker
Veloso, Manuela
Machine Learning
Recent years have seen a surge of machine learning approaches aimed at reducing disparities in model outputs across different subgroups. In many settings, training data may be used in multiple downstream applications by different users, which means it may be most effective to intervene on the training data itself. In this work, we present FairWASP, a novel pre-processing approach designed to reduce disparities in classification datasets without modifying the original data. FairWASP returns sample-level weights such that the reweighted dataset minimizes the Wasserstein distance to the original dataset while satisfying (an empirical version of) demographic parity, a popular fairness criterion. We show theoretically that integer weights are optimal, which means our method can be equivalently understood as duplicating or eliminating samples. FairWASP can therefore be used to construct datasets which can be fed into any classification method, not just methods which accept sample weights. Our work is based on reformulating the pre-processing task as a large-scale mixed-integer program (MIP), for which we propose a highly efficient algorithm based on the cutting plane method. Experiments demonstrate that our proposed optimization algorithm significantly outperforms state-of-the-art commercial solvers in solving both the MIP and its linear program relaxation. Further experiments highlight the competitive performance of FairWASP in reducing disparities while preserving accuracy in downstream classification settings.
title FairWASP: Fast and Optimal Fair Wasserstein Pre-processing
topic Machine Learning
url https://arxiv.org/abs/2311.00109