Search Results for author: Nicolas Boumal

Found 9 papers, 3 papers with code

Generalization of Quasi-Newton Methods: Application to Robust Symmetric Multisecant Updates

no code implementations6 Nov 2020 Damien Scieur, Lewis Liu, Thomas Pumir, Nicolas Boumal

Quasi-Newton techniques approximate the Newton step by estimating the Hessian using the so-called secant equations.

Optimization and Control Numerical Analysis Numerical Analysis

Efficiently escaping saddle points on manifolds

no code implementations NeurIPS 2019 Chris Criscitiello, Nicolas Boumal

Specifically, for an arbitrary Riemannian manifold $\mathcal{M}$ of dimension $d$, a sufficiently smooth (possibly non-convex) objective function $f$, and under weak conditions on the retraction chosen to move on the manifold, with high probability, our version of PRGD produces a point with gradient smaller than $\epsilon$ and Hessian within $\sqrt{\epsilon}$ of being positive semidefinite in $O((\log{d})^4 / \epsilon^{2})$ gradient queries.

Low-Rank Matrix Completion

Smoothed analysis of the low-rank approach for smooth semidefinite programs

no code implementations NeurIPS 2018 Thomas Pumir, Samy Jelassi, Nicolas Boumal

In order to overcome scalability issues, Burer and Monteiro proposed a factorized approach based on optimizing over a matrix Y of size $n$ by $k$ such that $X = YY^*$ is the SDP variable.

Retrieval

The non-convex Burer-Monteiro approach works on smooth semidefinite programs

1 code implementation NeurIPS 2016 Nicolas Boumal, Vladislav Voroninski, Afonso S. Bandeira

Semidefinite programs (SDPs) can be solved in polynomial time by interior point methods, but scalability can be an issue.

Optimization and Control Numerical Analysis

A Riemannian low-rank method for optimization over semidefinite matrices with block-diagonal constraints

1 code implementation1 Jun 2015 Nicolas Boumal

We propose a new algorithm to solve optimization problems of the form $\min f(X)$ for a smooth function $f$ under the constraints that $X$ is positive semidefinite and the diagonal blocks of $X$ are small identity matrices.

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