D-GAN: Divergent generative adversarial network for positive unlabeled learning and counter-examples generation
Authors: Florent CHIARONI. Mohamed-Cherif RAHAL. Nicolas HUEBER. Frédéric DUFAUX.
Keywords: Representation learning. Generative Adversarial Network (GAN). Positive Unlabeled learning. Image classification
TL;DR: A new two-stage positive unlabeled learning approach with GAN
Abstract: Positive Unlabeled (PU) learning consists in learning to distinguish samples of our class of interest, the positive class, from the counter-examples, the negative class, by using positive labeled and unlabeled samples during the training. Recent approaches exploit the GANs abilities to address the PU learning problem by generating relevant counter-examples. In this paper, we propose a new GAN-based PU learning approach named Divergent-GAN (D-GAN). The key idea is to incorporate a standard Positive Unlabeled learning risk inside the GAN discriminator loss function. In this way, the discriminator can ask the generator to converge towards the unlabeled samples distribution while diverging from the positive samples distribution. This enables the generator convergence towards the unlabeled counter-examples distribution without using prior knowledge, while keeping the standard adversarial GAN architecture. In addition, we discuss normalization techniques in the context of the proposed framework. Experimental results show that the proposed approach overcomes previous GAN-based PU learning methods issues, and it globally outperforms two-stage state of the art PU learning performances in terms of stability and prediction on both simple and complex image datasets.