  In continual learning, networks confront a trade-off between stability and
plasticity when trained on a sequence of tasks. To bolster plasticity without
sacrificing stability, we propose a novel training algorithm called LRFR. This
approach optimizes network parameters in the null space of the past tasks'
feature representation matrix to guarantee the stability. Concurrently, we
judiciously select only a subset of neurons in each layer of the network while
training individual tasks to learn the past tasks' feature representation
matrix in low-rank. This increases the null space dimension when designing
network parameters for subsequent tasks, thereby enhancing the plasticity.
Using CIFAR-100 and TinyImageNet as benchmark datasets for continual learning,
the proposed approach consistently outperforms state-of-the-art methods.
