Knowledge Distillation in Deep Networks Under a Constrained Query Budget
摘要
Knowledge distillation addresses the problem of training a lightweight model (student) from a deeper, more complex model (teacher) so as to mimic its performance. Existing techniques mostly utilize the predictions furnished by the teacher on a given training set to perform the distillation and train the student. However, querying the teacher model for labels can be an expensive process in terms of computational/ financial overhead. In this paper, we tackle the problem of distilling knowledge from a blackbox teacher model into a student deep neural network, in a cost-efficient manner. Active learning algorithms automatically identify the salient and exemplar samples from large amounts of unlabeled data and are instrumental in reducing human annotation effort in inducing a machine learning model. We propose a novel active learning algorithm using which the student model can identify the most informative samples from a large amount of unlabeled data, which need to be queried from the teacher. We exploit the geometry of the unlabeled data to identify a batch of representative samples which can reconstruct the data with minimal error. We pose the sample selection as an NP-hard optimization problem and solve it efficiently using an iterative algorithm, with global convergence. Such an algorithm can be effective in distilling relevant knowledge from the teacher to the student under a constrained query budget. Our extensive empirical studies on five challenging datasets from two application domains (computer vision and text mining) corroborate the efficacy of our active sampling framework over competing baselines.