Sketch-and-Project Meets Newton Method: Global $\mathcal O(k^{-2})$ Convergence with Low-Rank Updates
- URL: http://arxiv.org/abs/2305.13082v4
- Date: Mon, 27 May 2024 10:10:06 GMT
- Title: Sketch-and-Project Meets Newton Method: Global $\mathcal O(k^{-2})$ Convergence with Low-Rank Updates
- Authors: SlavomÃr Hanzely,
- Abstract summary: We propose the first sketch-and-project Newton method with fast $mathcal O(k-2)$ global convergence rate for self-concordant functions.
SGN inherits best of all three worlds: cheap iteration costs of sketch-and-project methods, state-of-the-art $mathcal O(k-2)$ global convergence rate of full-rank Newton-like methods and the algorithm simplicity of damped Newton methods.
- Score: 1.592855981846993
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: In this paper, we propose the first sketch-and-project Newton method with fast $\mathcal O(k^{-2})$ global convergence rate for self-concordant functions. Our method, SGN, can be viewed in three ways: i) as a sketch-and-project algorithm projecting updates of Newton method, ii) as a cubically regularized Newton ethod in sketched subspaces, and iii) as a damped Newton method in sketched subspaces. SGN inherits best of all three worlds: cheap iteration costs of sketch-and-project methods, state-of-the-art $\mathcal O(k^{-2})$ global convergence rate of full-rank Newton-like methods and the algorithm simplicity of damped Newton methods. Finally, we demonstrate its comparable empirical performance to baseline algorithms.
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