%0 Journal Article %T When Are Nonconvex Problems Not Scary? %A Ju Sun %A Qing Qu %A John Wright %J Mathematics %D 2015 %I arXiv %X In this paper, we focus on nonconvex optimization problems with no "spurious" local minimizers, and with saddle points of at most second-order. Concrete applications such as dictionary learning, phase retrieval, and tensor decomposition are known to induce such structures. We describe a second-order trust-region algorithm that provably converges to a local minimizer in polynomial time. Finally we highlight alternatives, and open problems in this direction. %U http://arxiv.org/abs/1510.06096v1