A generic approach for escaping saddle points

S Reddi, M Zaheer, S Sra, B Poczos… - International …, 2018 - proceedings.mlr.press
International conference on artificial intelligence and statistics, 2018proceedings.mlr.press
A central challenge to using first-order methods for optimizing nonconvex problems is the
presence of saddle points. First-order methods often get stuck at saddle points, greatly
deteriorating their performance. Typically, to escape from saddles one has to use second-
order methods. However, most works on second-order methods rely extensively on
expensive Hessian-based computations, making them impractical in large-scale settings. To
tackle this challenge, we introduce a generic framework that minimizes Hessian-based …
Abstract
A central challenge to using first-order methods for optimizing nonconvex problems is the presence of saddle points. First-order methods often get stuck at saddle points, greatly deteriorating their performance. Typically, to escape from saddles one has to use second-order methods. However, most works on second-order methods rely extensively on expensive Hessian-based computations, making them impractical in large-scale settings. To tackle this challenge, we introduce a generic framework that minimizes Hessian-based computations while at the same time provably converging to second-order critical points. Our framework carefully alternates between a first-order and a second-order subroutine, using the latter only close to saddle points, and yields convergence results competitive to the state-of-the-art. Empirical results suggest that our strategy also enjoys a good practical performance.
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