Scaffolding a Student to Instill Knowledge

Anil Kag, Durmus Alp Emre Acar, Aditya Gangrade, Venkatesh Saligrama

Keywords: knowledge distillation, tiny capacity student, large capacity teacher, budget constrained learning

Abstract: We propose a novel knowledge distillation (KD) method to selectively instill teacher knowledge into a student model motivated by situations where the student's capacity is significantly smaller than that of the teachers. In vanilla KD, the teacher primarily sets a predictive target for the student to follow, and we posit that this target is overly optimistic due to the student's lack of capacity. We develop a novel scaffolding scheme where the teacher, in addition to setting a predictive target, also scaffolds the student's prediction by censoring hard-to-learn examples. Scaffolding utilizes the same information as the teacher's soft-max predictions as inputs, and in this sense, our proposal can be viewed as a natural variant of vanilla KD. We show on synthetic examples that censoring hard-examples leads to smoothening the student's loss landscape so that the student encounters fewer local minima. As a result, it has good generalization properties. Against vanilla KD, we achieve improved performance and are comparable to more intrusive techniques that leverage feature matching on benchmark datasets.

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TL;DR: We develop a novel KD scheme where the teacher scaffolds the student's prediction on hard-to-learn examples. It smoothens student's loss landscape so that the student encounters fewer local minima. As a result it has good generalization properties.