  Stochastic variance reduction algorithms have recently become popular for
minimizing the average of a large, but finite number of loss functions. The
present paper proposes a Riemannian stochastic quasi-Newton algorithm with
variance reduction (R-SQN-VR). The key challenges of averaging, adding, and
subtracting multiple gradients are addressed with notions of retraction and
vector transport. We present convergence analyses of R-SQN-VR on both
non-convex and retraction-convex functions under retraction and vector
transport operators. The proposed algorithm is evaluated on the Karcher mean
computation on the symmetric positive-definite manifold and the low-rank matrix
completion on the Grassmann manifold. In all cases, the proposed algorithm
outperforms the state-of-the-art Riemannian batch and stochastic gradient
algorithms.
