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Minimax Classifier with Box Constraint on the Priors
Proceedings of the Machine Learning for Health NeurIPS Workshop, PMLR 116:66-80, 2020.
Abstract
Learning a classifier in safety-critical applications like medicine raises several issues. Firstly, the class proportions, also called priors, are in general imbalanced or uncertain. Secondly, the classifier must consider some bounds on the priors taking the form of box constraints provided by experts. Thirdly, it is also necessary to consider any arbitrary loss function given by experts to evaluate the classification decision. Finally, the dataset may contain both categorical and numerical features. To deal with both categorical and numerical features, the numerical attributes are discretized. When considering only discrete features, we propose in this paper a box-constrained minimax classifier which addresses all the mentioned issues. We derive a projected subgradient algorithm to compute this classifier. The convergence of this algorithm is established. We finally perform experiments on the Framingham heart database for illustrating the relevance of our algorithm in health care field.