  Collaborative learning has successfully applied knowledge transfer to guide a
pool of small student networks towards robust local minima. However, previous
approaches typically struggle with drastically aggravated student
homogenization when the number of students rises. In this paper, we propose
Collaborative Group Learning, an efficient framework that aims to diversify the
feature representation and conduct an effective regularization. Intuitively,
similar to the human group study mechanism, we induce students to learn and
exchange different parts of course knowledge as collaborative groups. First,
each student is established by randomly routing on a modular neural network,
which facilitates flexible knowledge communication between students due to
random levels of representation sharing and branching. Second, to resist the
student homogenization, students first compose diverse feature sets by
exploiting the inductive bias from sub-sets of training data, and then
aggregate and distill different complementary knowledge by imitating a random
sub-group of students at each time step. Overall, the above mechanisms are
beneficial for maximizing the student population to further improve the model
generalization without sacrificing computational efficiency. Empirical
evaluations on both image and text tasks indicate that our method significantly
outperforms various state-of-the-art collaborative approaches whilst enhancing
computational efficiency.
