AdaDFKD: Exploring adaptive inter-sample relationship in data-free knowledge distillation

In scenarios like privacy protection or large-scale data transmission, data-free knowledge distillation (DFKD) methods are proposed to learn Knowledge Distillation (KD) when data is not accessible. They generate pseudo samples by extracting the knowledge from teacher model, and utilize above pseudo samples for KD. The challenge in previous DFKD methods lies in the static nature of their target distributions and they focus on learning the instance-level distributions, causing its reliance on the pretrained teacher model. To address above concerns, our study introduces a novel DFKD approach known as AdaDFKD, designed to establish and utilize relationships among pseudo samples, which is adaptive to the student model, and finally effectively mitigates the aforementioned risk. We achieve this by generating from "easy-to-discriminate"samples to "hardto-discriminate"samples as human does. We design a relationship refinement module (R2M) to optimize the generation process, wherein we learn a progressive conditional distribution of negative samples and maximize the log-likelihood of inter-sample similarity of pseudosamples. Theoretically, we discover that such design of AdaDFKD both minimize the divergence and maximize the mutual information between the distribution of teacher and student models. Above results demonstrate the superiority of our approach over state-of-the-art (SOTA) DFKD methods across various benchmarks, teacher-student pairs, and evaluation metrics, as well as robustness and fast convergence.