The Role of Entropy and Reconstruction in Multi-View Self-Supervised
  Learning
Authors: name: Borja Rodríguez-Gálvez, name: Arno Blaas, name: Pau Rodríguez, name: Adam Goliński, name: Xavier Suau, name: Jason Ramapuram, name: Dan Busbridge, name: Luca Zappella

The mechanisms behind the success of multi-view self-supervised learning
(MVSSL) are not yet fully understood. Contrastive MVSSL methods have been
studied through the lens of InfoNCE, a lower bound of the Mutual Information
(MI). However, the relation between other MVSSL methods and MI remains unclear.
We consider a different lower bound on the MI consisting of an entropy and a
reconstruction term (ER), and analyze the main MVSSL families through its lens.
Through this ER bound, we show that clustering-based methods such as
DeepCluster and SwAV maximize the MI. We also re-interpret the mechanisms of
distillation-based approaches such as BYOL and DINO, showing that they
explicitly maximize the reconstruction term and implicitly encourage a stable
entropy, and we confirm this empirically. We show that replacing the objectives
of common MVSSL methods with this ER bound achieves competitive performance,
while making them stable when training with smaller batch sizes or smaller
exponential moving average (EMA) coefficients.
  Github repo: https://github.com/apple/ml-entropy-reconstruction.