Projected estimators for robust semi-supervised classification
By Jesse H. Krijthe, Marco Loog. 2016
21 citations recorded by the source corpus.
For semi-supervised techniques to be applied safely in practice we at least want methods to outperform their supervised counterparts. We study this question for classification using the well-known quadratic surrogate loss function. Unlike other approaches to semi-supervised learning, the procedure proposed in this work does not rely on assumptions that are not intrinsic to the classifier at hand. Using a projection of the supervised estimate onto a set of constraints imposed by the unlabeled data, we find we can safely improve over the supervised solution in terms of this quadratic loss. More specifically, we prove that, measured on the labeled and unlabeled training data, this semi-supervised procedure never gives a lower quadratic loss than the supervised alternative. To our knowledge this is the first approach that offers such strong, albeit conservative, guarantees for improvement over the supervised solution. The characteristics of our approach are explicated using benchmark datasets to further understand the similarities and differences between the quadratic loss criterion used in the theoretical results and the classification accuracy typically considered in practice.
Subfields: Artificial Intelligence, Statistics and Probability
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Citations in the corpus
- Dash: Semi-Supervised Learning with Dynamic Thresholding (2021, background): “An non-exhaustive list of those studies include [Cozman et al., 2003, Singh et al., 2009, Li and Zhou, 2011a, Balsubramani and Freund, 2015, Loog, 2015, Li et al., 2017, Krijthe and Loog, 2017, Li et al., 2021, Mey and Loog, 2019, Guo et al., 2020].”