SATE: Efficient knowledge distillation with implicit student-aware teacher ensembles

Recent findings suggest that with the same teacher architecture, a fully converged or “stronger” checkpoint surprisingly leads to a worse student. This can be explained by the Information Bottleneck (IB) principle, as the features of a weaker teacher transfer more “dark” knowledge because they maintain higher mutual information with the inputs. Meanwhile, various works have shown that severe teacher-student structural disparity or capability mismatch often leads to worse student performance. To deal with these issues, we propose a generalizable and efficient Knowledge Distillation (KD) framework with implicit Student-Aware Teacher Ensembles (SATE). The SATE framework simultaneously trains a student network and a student-aware intermediate teacher as a learning companion. With the proposed co-training strategy, the intermediate teacher is trained gradually and forms implicit ensembles of weaker teachers along the learning process. Such a design enables the student model to retain more dark knowledge for better generalization ability. The proposed framework improves the training scheme in a plug-and-play way so that it can be applied to improve various classic and state-of-the-art KD methods on both intra-domain (up to $2.184\%$) and cross-domain (up to $7.358\%$) settings, under a diversified configurations on teacher-student architectures, and achieves a major efficient advantage over other generic frameworks. The code is available at https://github.com/diqichen91/SATE.git.